Yes and no. Some smokers live to be a 100, and some Saints did smoke. However, it is generally agreed that smoking is injurious to health.
One can argue from the standpoint that the body is the Temple, vehicle or instrument of the Spirit. It is also a known fact that when we are sick or suffer from infirmity, we do not pray or sit in Silence so well, as our aches and anxieties soon come to the fore. So in that sense it's harmful, along with many other things that affect our ability to relate to God.
My Spiritual Teacher always recommended a healthy, wholesome lifestyle for spiritual pursuit. I can tell you from my own experience, that when the Higher Forces descend in prayer, they can be so powerful that the inner vessel needs to be strong enough to receive and assimilate the experience. Much Love.