Hello Bara
I have read the posts posted. I am a gambler on and off for the last 30 years. I am what you call a binge gambler. It is very hard for a gambler to let go of what they lost and the aim is each day i am more experienced and that i wont make that same mistake again. However in reality it just doesnt work. Unless he has self control which only 2 or 3 in a hundred do he will continue.
In reference to him opening a account under your name the money has to come out of your account unless he uses another method of payment which does not disclose who the receiptant is.
In reference to him self excluding he will have a copy of the agreement. If he has self excluded you can ask him for how long i believe the minimum is 3 months to a maximum of 5 years.( this applies in the UK other parts i am not sure) You can do a test on this by applying to a online company using his details if he has self excluded you wont be able to open a account.
I wish you all the best.