it depends on why the funds is left on the closed account. I mean, when it comes to money laundering, the government usually confiscate the funds after the casino has reported it and the government has done its investigation. but to be honest, I don't really know what happens if the funds on the closed account are not related to money laundering, maybe after some time the casino just considers it as their own property or maybe they would still need to give it up to the government as per regulation or something.