Are there any gay fitness/physique/bb Youtubers that are popular?

Well, Scooby has more followers than any of the people you named. I don't think he's "popular" the way those people are popular though. He does mostly instructional videos.

My experience is that gay guys tend to be pretty popular on Instagram but don't have a big Youtube presence. And the Instagram ones are more of a male model/physique hybrid - not really major lifters or ultra jacked the way those people are (a lot of them seem to be underwear or fashion models). Here are some that are pretty popular - most around 100k-500k followers.

/r/bodybuilding Thread