Speaking from my experience, it is highly advisable to quit smoking / tobacco / nicotine.
Personally I have quitted on alcohol, tobacco/nicotine, caffeine (in all forms i.e. cafe, tea, cocoa), and refined sugar (including all products with added sugar) as I felt those have strongly interfered with my spiritual practice and mood. Of course it happened gradually over a period of few years and sometimes I allow myself for some exceptions when the situation requires e.g. drink a coffee when I'm tired and have to drive a car for couple of hours.