well it doesn't make it better, at least it doesn't make their physical condition better, if it helps
psychologically is harder to define, there is a case that some people have a phycological disposition towards smoking and if they weren't doing that they would be doing something else equally bad or worse at least as far as conditioning goes,
not many youngsters smoke these days, however there is an epidemic of energy drink abuse, loading your self with caffeine and sugar doesn't strike me as a good idea either, they only seem to imbibe tobacco in order to get their cannabis down, which they need to off set the effects of the energy drinks
a strange amount of top class athletes seem to smoke, this is certainly true of soccer players, rugby players and cricketers, perhaps less true of disciplines which are entirely cardio based, hard to say those that do tend to try and hide it. in order to be a good role model.
they also seem to involve themselves with alcohol and various recreational drugs which also don't help performance
non of this seems to mean they cant be top class athletes so the main question would be, would they be better if they didn't ? don't know, no data