Neither the Landlord nor the Tenant have the right to unilaterally impose changes to the terms of the tenancy as the Landlord is trying to do by saying that you can no longer smoke in your apartment. ON THE OTHER HAND your Landlord can give you a so-called 30 day notice of termination of your tenancy if you are a tenant at will and he chooses to do so, or he may decline to extend the term of your lease when it is expiring if you have a lease.
Note that without a personal consultation it is not possible to gather all the facts of your situation, fully evaluate it, and offer specific legal advice. It is almost the rule that when a client meets with an attorney, other facts are developed that put both the legal and practical situation into a different light and resulting in different comments and advice than might have been given after the lawyer only has a brief conversation with the potential client. As such the above general comments and questions may not be taken as legal advice and should not be followed without first speaking with an attorney about the specifics of your situation in more detail so that appropriate advice may be given.