Can my landlord raise my rent (NJ)?

So I've just signed a lease with 3 other guys (four total) and have been living there for two weeks (it is a 4 BR apartment in NJ)... When my landlord came by two of us had girlfriends there, brinigng the total to 6 people living there...now my GF is only living there two months while the other girl is going to live there for a year... Now my landlord got in touch with me today and said that a 'tenant' is defined as someone living there for a total of 30 days, consecutive or not, out of the year and if thats the case that they have to be added to the lease. This i can understand an am OKAY with. My question is the landlord is also requesting that we pay extra money per month per additional tenant...now the lease specifically states our rent and the Landlord only pays cold water and sewage for utilities and there are no provisions about how many people can live there etc... can my landlord request this raise? also does the landlord hold the right to simply say our girlfriends cant live there?