Anyway, he is making a lot of money just by playing some slots and entertaining people with his reactions.
He has made it profession and you see he is doing quite well in that like earning good amount from these sponsored deals from different casinos, giving away to the viewers and then secondary income from steaming platforms and preety sure he streams on various platforms along with YouTube.So he's earning by entraining people and himself by just gambling.
It is not even that easy to get people to watch you. Just to give an example, God of War came to PC recently, which made A LOT of streamers to play it on their platform. This meant that for a while that was the most played game, just like when it first came out, but some people had 10 viewers, some had 100k viewers, and that's the difference. Same game, so it is not like "you just sit there and play a game", if that was the case then 10 vs 100k difference wouldn't happen since they are both doing the same thing.
The difference is what you bring to the table, if you are good and liked then people would watch you, if you are not then people would stop and go to some other streamer. This is the same thing, people can gamble, you can gamble, you can also open up a twitch stream or whatever platform and gamble live, nothing stops you, BUT would you be able to get as many viewers as these people? Doubtful.