The title of the article is misleading. He didn't steal it, he cheated the casino out of it. This is an important distinction since in the eyes of the law the casino willingly gave him the money when he cashed out. The casino can catch you cheating and prevent you from cashing out, but once you're out the door you're pretty much free (although I probably wouldn't come back).

In fact the article actually says they've identified the man and banned him from the casino. If they had legal backing I'm sure it would have mentioned the manhunt, and not a "near zero chance of recovering the money."

Or they are just making it up and using this as an excuse to never allow him to play in their casinos

If they want to ban somebody, they don't need to make up a fake story and get it in the news, they just ban them

Sure, but they need a good story if they want to recover a $33m loss.

Given that it's an Australian casino, its highly likely that the gambler is associated with a syndicate working out of Southeast Asia (see for example the recent soccer gambling scandal). The problem isn't identifying who took the money, the problem is a) prosecuting and b) identifying and recovering assets in a tangle of opaque foreign legal systems.