Just about all modes of treatment for drug addiction, for just about all drugs, have about a five percent "success" rate per year. "Success" meaning abstinence. The only real exception is drug substitution -- taking another drug, or another form of the drug (such as nicotine patches), for the original drug.
The key to hypnosis is simply believing that it is going to work for you. But, of course, if you believe it is going to work, why do you need to be hypnotized? Success presumes a certain amount of what would be called gullibility in any other setting.
Probably can't hurt -- except the wallet if someone is paying for it.
Just FYI, heroin addicts commonly report that it is tougher to kick tobacco than it is to kick heroin -- which is why heroin recovery programs don't try to get their clients off of tobacco, even though the tobacco is about 100 times as likely to wind up killing them. The reason it is tougher to kick is because the cravings last longer.
Good luck.