Quick math
There are about 4 billion women in the world And about 4 billion men.
About 5% of men are gay, let's round that up to 10% to account for closeted gays. I'll use the same value for women.
So we've got 3.6 billion straight women vs 0.4 billion gay men.
9 times more straight women than gay men.
So a gay man would have to, on average, give a blowjob 9 times more frequently than a woman to break even.
So the question is, how often does the average woman give a blowjob? Let's go conservatively and say one a week? Some will be more, some will be less. Which means gay men will need to give a blowjob more than once a day on average, which seems unlikely.
But let's say it's far lower than what I'm thinking, if the average woman gives a blowjob once a month, gay men would need to give a blowjob every 3 days. That's certainly achievable.
I think the answer is straight women, in my experience gay men aren't as horny as people would have you believe, and women are way hornier than people would have you believe.
However, I say this as a married straight guy with a lot of women friends and a few gay friends so take this with a grain of salt