First, no activity is "gay". Being gay means being attracted to other men sexually and or romantically. You could jerk off with a video of two guys having sex all day long and still be straight if you didn't find it attractive.

Second, both lesbian and gay porn is 100% gay because it is literally gay sex. Streight poem is 50% gay because (assuming you're cis) one of those people is the same gender as you. On the other hand, porn in which someone who has a penis and breasts has sex with a female-bodied person is only 25% gay, as it contains 3 sexualized parts and 1 male sexualized part. For minimum gay-ness you should watch porn which has as many women as possible in it, to lower the percentage of gay-ness.