A lot of those streamers are pretty open about how twitch revenue is a small portion of their earnings.

Ninja was famously paid $1MM for an 8 hour ad of playing Apex at launch.

I've had private conversation with large streaming friends that have all said independently that the amount they get paid from a short Raid Shadow Legends ad is huge. One said it's enough to buy a nice car, and if they hit their target downloads (w/ link) the number jumps up to enough to buy multiple nice cars.

There is a lot of big money for streamers, not just big streamers.