I think its impossible to stop once you have been addicted, no mater what you do.
it can be done but it cannot be an immediately action. you must learn how to adjust to it and that may takes time. you can try to reduce the urge, duration of gambling, amount gamble etc. so in the long run, it is possible to stop the addiction but it is still depend heavily on the user.
I believe that once someone knows that they are addicted,
they can do something about it.
This is harder for people who don't realize they are addicted