It really depends on what one's revenue model is. There's a lot of potential for viral discoverability thanks to the 'boost' propagation model of the fediverse, and so direct sponsorships should be maintainable, given a growing and engaged population here.

End-cap and interstitial ads revenue is much more complicated issue. Advertisers that like dealing with single entities, like YouTube or Twitch, are going to be a completely different nut to crack. And that's assuming PeerTube admins have, or gain access to, instance-level ad management tools.

But it's doable. It'll require some work, and an active audience, but it's right at a cusp.