I don't have precise figures, but I would wager that there are far less pilots who smoke now than ten years ago.
Giving up smoking is a tough call, for the very reasons you stated, but if you can do it now it could save you a miriad of problems in later life.
A close friend of mine has just had his class one medical pulled, he's fitter than any pilot or atco I've ever met, exercises in the gym every day, and the reason he's lost his ticket? Following extensive tests it transpires that he has heart and lung problems directly attributable to smoking a pipe twice a day - correct me if I am wrong, but I understand tha pipe smokers don't directly inhale - although the secondary smoke must have some effect.
I honestly don't know how the result of the above tests were concluded, all I know is that it included Doctors, consultants, specialists and several months before the medical was finally pulled.
A reasonable incentive to quit methinks.