Gorilla.... probably.

No direct comparison of Gorilla to human strength has been made, however tests on chimps have shown the to be 4 to 8 times as strong as a similarly sized human. Now given the size difference between a gorilla and a chimp and witness accounts of Gorilla feats of strength likely estimates of a gorilla compared to a man range from 8 - 20 times.

Obviously the eight Brock Lesners only just crosses the minimum human strength of a gorilla, however the comparisons were done between a chimp and human of similar weight, this is about 60kg, Brock is about twice that so about past midway up the scale, as in in the given situation a Lesnar is worth two chimp sized men.

You'd need an estimated 8 - 20 men and the Brocks are worth 16. By no means a guaranteed victory but 2:3 odds in favour of the Brocks... however, only in a strength for strength contest!

And, since we're not talking tug-of-war here there are other factors to consider, a punch from Brock would likely anger the gorilla, a punch from the gorilla would flatten a Brock... we're potentially talking about a punch 50% stronger than all eight Brocks hitting simultaneously. Plus teeth being bitten by a gorilla is like being stabbed multiple times, being bitten by Brock through thick hide is tedious at worst.

A well synchronised simultaneous eight pronged attacked and the Brocks could take down the gorilla and use bars and locks to incapacitate it on the ground, but if the gorilla gets its hands on any one Brock individually it would rip him pieces in seconds...

So could the Brocks do it? Yes, with luck on their side and a solid plan they probably could in theory. Would i bet on them doing it? Hell no, money on the gorilla every time.