Without a doubt the support from your family members is necessary in order to recover from a severe case of gambling addiction and a change in the environment can without a doubt help those which were addicted, but even that is not enough, professional help is needed as well otherwise it would be incredibly easy for that person to go back to his old ways, and we have many examples of this on the forum, in which they can leave gambling for a while but eventually they go back to it and lose a massive amount of money in a short amount of time.
That's the problem, just the same with any addiction. If there's no self will, the person can easily go back and got engage. It's an effort coming first with the person itself to solve his problem, plus the support of the family and love ones which will be extended to seek help with the professionals, in this process the addiction will be easier to remove from that particular person's system.
It's an effort that will work if the person itself is willing to clean and free himself from addiction.