Looking at this from a standard point of view, I don't think statement from this will be actually accepted by this casino as proof of source of income, since they aren't generally legal and acceptable with an official name and home address of the user in question, if not I would have suggested you use "Blockchair explorer" to generate a statement showing the inflow and outflow of Bitcoin into a  wallet. But I doubt if this will be accepted as legal documents, that's why it will be better you go use your Utility bill for such approval.