I'm fifteen so I don't have much room to talk, but I've been told that I'm living 5 years ahead of my time.

If theres one thing I've learned its this, at 14, its not worth altering ones life completly for a girl. Not only that, but it sounds like your friend is being a bit of a douche in the process.

Make sure he realises that if he has to quit for this girl, then shes probably not worth his time. You don't want him hurt, and with wasted time not smoking, do you?