Frankly you should assume that anyone who is streaming gambling related content is going to be compensated by a gambling operation in some way. The commissions that gambling companies can afford to pay are some of the highest advertising rates you'll find. If you picture gambling sites are pure money making machines, because players pay so much in and very rarely take anything back out again, every new depositing customer they can get from any source is super valuable. There are lots of different ways it can be "faked" as well, credits simply added to the account so they're never playing with their own money or even an external contract where they get paid a sum to their bank for the service, then deposit it to make it look entirely natural.