I think Mark (69 CE) and the First Edition to John (<70 CE) date pre 70CE. Keep in mind that the Gospel also use sources that antedate 70, like the Passion Narrative (<37 CE)1 and Q Document (30-50s CE)2 3 4
There is no material in Mark which must be dated after 70
(E.P Sanders and Margaret Davies, Studying The Synoptic Gospels, p. 18).
Here I will only examine the most important datums with regards to the date of Mark.
See here for an inquiry on who the author was.
Mark 13:1-2
As he came out of the temple, one of his disciples said to him, “Look, Teacher, what large stones and what large buildings!” 2 Then Jesus asked him, “Do you see these great buildings? Not one stone will be left here upon another; all will be thrown down.”
There are many reasons to think that this passage does not demand a post-70 date and is, at least, equally likely consistent with a date in the late 60s C.E.
1) Joel Marcus makes this observation:
On one hand, in favor of a pre-70 dating is the probablity that Jesus actually prophesies the Temple’s destruction, as did other Jewish prophets down through the centuries (see e.g jer 7:1-15; Josephus J.W 6.300-9; cf. Brown, death, 1.450, and Evans, “Non-Christian Sources,” 475-77); a prophecy of its end, therefore, would not require a post-70 date.
(Joel Marcus, Mark 1-8, Anchor Yale Bible Commentaries, 2009, p. 38)
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2) "The saying, especially the phrase “a stone upon a stone” (λίθος ἐπὶ λίθον), does not correspond to any surviving description of the destruction of the First or Second Temple. Rather, it depicts a reversal of the allusion to the building of the Second Temple in Haggai:
And now call to mind, from this day backward, before the placing of a stone upon a stone in the temple of the Lord, what sort of people were you? (Hag 2:15–16a LXX)
(Adela Y. Collins, Mark: A Commentary, Hermeneia, 2007, p. 602.)
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3) Adela Y. Collins writes: "As noted above, some have argued that the prediction placed in the mouth of Jesus in v. 2* implies that the temple had already been destroyed when Mark wrote his Gospel. Such a conclusion is not necessary. That the conclusion is not necessary is shown by the comments above and also by a remark of Josephus, who observed that the speeches of John of Gischala seduced most of the youth and incited them to war:
but of the sober and elder men there was not one who did not foresee the future and mourn for the city as if it had already met its doom (Bell. 4.3.2 §128).
Surely Josephus’s remark owes something to hindsight, but once the war had begun, anyone, especially one who knew the Jewish scriptures, could have come to the conclusion that it would end in the destruction of the temple and the city of Jerusalem." (Adela Y. Collins, Mark, Hermeneia, 2007, p. 607-608)
Other figures recorded by Josephus "predicted" the temple and the city's fall as well.
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4) Mark makes no mention of the huge fire that aided the temples collapse which killed hundreds or thousands of Jews, even though this fire features predominately in post-70 CE accounts of the war (Josephus J.W. 6.250-87; Dio Cassius 66.6; ‘Abot R. Nat. [B]7{Saldarini 72-73]; cf. b. Ta’an 29a). While I'm not as confident as Casey, he writes: "One of the most famous aspects of the destruction of the Temple was that it was burnt down (Jos. War VI, 250–84). It is accordingly inconceivable that a pseudo-prophecy written after these dramatic events should omit the centre of the drama, the burning down of the whole Temple." (Casey, Jesus of Nazareth, 2010, p. 69)
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The implication here is that v. 2 was not necessarily written after the temple was destroyed in 70 CE. It could equally likely have been written before the Roman siege of Jerusalem. Mark could have anticipated the destruction of Jerusalem and the temple at any time after 68 and have seen the hand of God in the impending destruction. If Mark was written in Rome, than the Roman civil war of 69 CE serves as a perfect date for the eschatological apocalypse, where the world looked it was falling apart with the Jewish war occurring in Jerusalem and the Roman civil war, as bloody but brief as it was, occurring in Rome at the same time.
Mark 13:14
“But when you see the desolating sacrilege set up where it ought not to be (let the reader understand), then those in Judea must flee to the mountains
Adela Yarbro Collins writes:
Given the eschatological perspective of Mark and the analogies in the Dead Sea Scrolls, it is likely that the evangelist read the ex eventu prophecy of Dan 9:27* as a genuine prophecy of an event to take place in the last days. In the context of vv. 14–20*, it is implied that this event will initiate the second stage of the eschatological scenario, the “tribulation” (θλῖψις). Those who understand v. 2* as an ex eventu prophecy conclude that v. 14* is another of the same type. But the tribulation inaugurated by this event does not seem to be equivalent to the first Jewish war with Rome as a whole, since at least part of this war belongs to the first stage, the “beginning of the birth-pains” (ἀρχὴ ὠδίνων), as argued above. Some argue that the desolating sacrilege is the destruction of the temple as such, but this theory cannot explain the shift from the neuter noun to the masculine participle or why the sacrilege or abomination is said to be “standing.” Another possibility is that the term βδέλυγμα (“sacrilege” or “abomination”) refers to Titus’s inspection of “the holy place of the sanctuary” (τοῦ ναοῦ τὸ ἅγιον) when the chambers surrounding the temple were already burning (Bell. 6.4.7 §§260–61). But what sense would it make to encourage those in Judea to flee at that late stage of the war? And what would they be fleeing from?
Martin Hengel argued that the perspective of vv. 14–19* does not fit the situation during or after the conquest of the temple and the city, which took place in the period extending from July to September of 70 ce. Since Vespasian had subdued Judea and isolated Jerusalem already in 68 ce, an exhortation to its inhabitants to flee to the mountains in the desert of Judea would already at that time have made little sense. Once the siege was in place, refugees would have had to flee into the arms of the Romans or, if they managed to escape them, they might have encountered the equally murderous sicarii in and around Masada. In fact, in the period before the siege, rather than fleeing to the mountains, the rural population fled into the city. Those who remained in the countryside, who were not active rebels, no longer had to fear for their lives, and thus flight was more dangerous than staying put.
(Adela Y. Collins, Mark: A Commentary, Hermeneia, 2007, p. 608-609)
Mark 13:7
When you hear of wars and rumors of wars, do not be alarmed; this must take place, but the end is still to come.