Can states have gay marriage?
The states can have gay marriage imo. In order to prohibit gay marriage the Constitution would have to be amended to prohibit such marriage imo.
Also, regardless that the corrupt media would have everybody believe that the Supreme Court decided Defense of Marriage Act (DOMA) unconstitutional, Section 2 of DOMA is evidently still in effect.
Section 2. Powers reserved to the statesNo State, territory, or possession of the United States, or Indian tribe, shall be required to give effect to any public act, record, or judicial proceeding of any other State, territory, possession, or tribe respecting a relationship between persons of the same sex that is treated as a marriage under the laws of such other State, territory, possession, or tribe, or a right or claim arising from such relationship.
So regardless if a state allows gay marriage, states that don't allow gay marriage can basically ignore such marriages.