i have about 25 years of experience with folks going through the process of coming out to themselves and others that they're gay. sexual orientation falls along a continuum, with very few people being 100% straight or 100% gay. what seems consistent is that the farther you move toward the gay end of the continuum, the more likely you are to wonder whether you're gay. someone who is firmly in the straight end of the continuum will likely never question if they're gay or not. do they question if they're straight? however, if you find yourself wondering if you're gay, you may fall outside the certainly straight end of the continuum and have on a passing curiosity (what fetlife calls heteroflexible), be bisexual or perhaps you are gay. every spot on the continuum is equally valid and healthy. you are who you are. the more self-awareness you have, the better.
having a fetish and watching others engage in that fetish, regardless of gender, is not going to make someone gay. i'm don't think ANYTHING can make someone gay.