You haven't even proven that Gab is a white supremacist site. It's not. That's simply a mudslinging accusation meant to unfairly defame a site, probably because it contains different opinions than your own.
You can easily find antisemitic tripe in Gab's official account. It's a site run by bigots for bigots that likes to pretend it's some neutral, principled free speech crusader. It's thoroughly, painfully obvious to any reasonable person that it's not - it's just a generic online septic tank.
I don't recall running into much antisemitic tripe when I was there.
Calling Gab a white supremactist website just seems like a ridiculous over-the-top assertion without even a shred of evidence to back it up... I don't get how this isn't being called out as a blatant ad hominem attack.
Hm, thanks for the link! Definitely ridiculously unprofessional Twitter account they have. I wouldn't call them Nazis based on those tweets alone though. But yeah that certainly doesn't reflect well on them.