Does a landlord have a legal right to limit the number of occupants in a rental property?

Yes, a landlord *could* limit the number of occupants in a rental property, as long as that limitation is part  of the lease. Leases often do, in fact, limit the number of occupants. However, landlords cannot simply, arbitrarily impose this limitation whenever they want: it must either be in the lease or in some other document to which the lease refers (e.g. in some sort of house rules, for multifamily dwellings). If there's no written lease, then its an oral lease, which means each lease term is  only one month; that in turn means that with one month's notice, the landlord could put an occupancy limitation in place. Also, if the proposed occupancy exceeds the zoning in some fashion, then the landlord couldn't allow it to occur, even if he or she wanted to.

Generally speaking, a landlord has a right to limit not only the number of tenants that can occupy the premises but the purpose for which the property is used, pets and any other provision deemed necessary and probably reasonable.  Remember that a lease is a contract between you and the landlord so you do have a right to negotiate the terms of the contract between you so think that through as well. But also remember that it is HIS property and he wants to make sure that it does not become a boarding house of sorts.  There may also be a local law or ordinance that prohibits the number of occupants as well.  Good luck.