If I fell in love with him before knowing he was a smoker, I would keep dating him.
But if I knew it before, most likely it would draw a negative image of him on my mind and I wouldn't start doing so.
The smell of cigarettes is disgusting. I would not be able to handle that smell around me all the time. Plus, the money that goes towards buying cigarettes can be going towards buying me gifts.
A cigarette smoker could be a potential dealbreaker, but if he's perfect in every other way (highly unlikely) I would for fun/an obvious fling
Would I seriously date a cigarette smoker? Doubtful. If it were to become serious/long-term I wouldn't want to put myself in the position to lose another person to lung/heart related illnesses that come with it.
I have no problems dating a smoker. I have in the past and the smell has actually grown on me. Not to a point where I think it smells good, but acceptable.
If you count using e-cigs then I have absolutely no problem at all.