I suspect he did make money. The key would be to spread the wealth. Vegas has 104 casinos. If he won $500K a year, that's about $400 a month from each casino. Nobody's going to look at him twice for that kind of money. His specialty was video poker, where (according to the brother in one of the interviews) the payout was 99.37% plus hotel comps. The guy might have been Rain Man with numbers - he spent three years as an IBM auditor, and they don't hire dummies.
You won’t be able to get comped a room by 104 casinos in a month. That would be mathematically impossible. lol. Believe me, he would have been watched like a hawk because of the fact that he used to be an accountant. And the way he played. We already have a report from one casino worker that said he some times won. Heck, he could have been laundering money into the casino too.
Knowing numbers is not going to help you beat these machines. If you are consistently beating these machines, you will attract the attention of the Casino's security people pretty quickly, even if it's a small amount of money you win each time. If you are a regular, and they notice you are winning more than you are losing, they will start scrutinizing you.
If they can't figure out what you're doing, they will simply ban you.
It makes more sense that he was making his money some other way, and either gambling it to launder it, or just for fun.