Family and friends maybe can help addicted gambler to not "being addicted" again in gambling. But the one who can make they stop to play in gambling is themselves. (yourself)
Family and friends can distract the addicted gambler to do something else interesting. They should not lend a penny to the addicted. There is nothing wrong with the gambling itself. It somebody is addicted, it is the problem of the individual. Gambling should be fund, not stressful.