Yes, it is very possible that smoking will cause an individual to have impotence or (ED) which is Erectile Dis-function ...  because as we know smoking can cause severe damage to one's  blood vessels  
i think ED is  caused by poor blood supply to one's penis

so if one quit's  smoking there's a possibility that his impotence will go away... in other word he will be healed..  for cells of our body replace the dead ones..