If there is any advice you can give me on how to approach this matter please help.
It takes a gamble to understand a gamble and lead him to the right way, my advice is to help him find an anonymous gambler healing group and ask him politely to join the group these groups will help him overcome gambling by telling their own stories and find ways to help him overcome gambling and recommend him to undergo treatment from gambling facility manage by professionals.
It's hard to cure addiction to gambling and merely asking to stop him will not do good, you must lead him to people that he can trust to open up if he will not listen to close friends and family.
for you to end up on approaching other people on solving something which could really be solved out on your own.Its impossible that you cant be able to make self realizations, if things turns out to be hard
then you would be going into the last option.