A big part of streaming on Twitch or Youtube streams is donations from fans and subscribers/members (regular payments from fans). Royalties from advertising is a part of it, but a lot of the money comes in from donations. Another common approach is merchandise in the from of stickers and clothing, people love that stuff.
You can do well even as one of the smaller streamers if your community and other monetization is strong. I've never really gotten why people donate, especially to the bigger streamers since it's clear they already have money. But it's a big part of it. You can easily watch hundreds of dollars in an hour get donated to even to a smaller or mid level streamer.
The other stream I watch, most donations actually pay for the food of college students in Moscow, Idaho, USA, as the stream is a food truck in that town ;)
You can do well even as one of the smaller streamers if your community and other monetization is strong. I've never really gotten why people donate, especially to the bigger streamers since it's clear they already have money. But it's a big part of it. You can easily watch hundreds of dollars in an hour get donated to even to a smaller or mid level streamer.