I have a white coating on my touge does smoking cause this?

Multiple causes: Smoke, bacteria, mucous, irritation, infection, dental/oral issues are all possibilities: you should be examined by both a -physician and a dentist.

Perhaps: the rule of thumb is for all chronic white and red lesions in the mouth should be checked. Either a biopsy or proteomic biomarker testing (integrin alpha5beta1) can inform if there is pathology present on the tongue.