In what way? Gab was banned on most app stores as I understand it. Gab seems to be user financed which has historically paid out less than advertising. Mastodon basically blacklisted them everywhere it could (clients, instances, etc.) so they're not really part of the fediverse. Gab is for all intent and purposes not part of the Mastodon platform because Mastodon knew what would happen if it was.
Gab was indeed blacklisted in many (though not all?) Mastodon apps.
My point is that, since Gab "joined" Mastodon, nothing of what you have predicted happened to Mastodon. My hope is that the same things will (not) happen to Peertube, for the same reasons.
Except the point I responded to talked about marketing and a huge user increase. Mastodon hasn't gained marketing or users, Gab did. They use the same code mostly but are separate platforms for all intent and purposes. You can't have your candy and eat it too.
