Well smoking isn't just your main problem here obviously. Your strict fitness routine may affect the relationship as well. Also she may argue if u can have your fitness routine why can't just let her have her smoking routine? Most girl don't talk common sense anyway haha. U'll just need to thread this through slowly and steadily if u are really into her.
Try talk to her, expose her to ideas and opinions that smoking is not healthy especially to those around her. If she is really into you, she will stop smoking.
However i reserve my doubt as with what other forumer said, she may stop smoking for u but there are high chances that she may pick back the bad habit during the stages in life. If u can bear the risk of that, go ahead, otherwise find other.
Dating a girl that ... smokes