NTA There's not much more that I can directly say about why you're in the right which hasn't been said so I'll just say this in case you end up wanting to give him some advice about streaming.

Quit Fortnite. I don't know the scene at all but it's been put long enough for it to be so saturated (or maybe even dying out) that without a huge serving of luck and amazing charisma, he's got no chance or making it. If he truly wants to be a streamer, he has to be bold and stream the newest games, either those with a lot of hype or those he thinks will be big. He'll still need a lot of luck and charisma but he stands a better chance than going against well established streamers.