They have the power to control immigration policy. States decide their own policy on marriage, and military and federal employees have to comply with the laws of the state they're in. Being federal employees does not make them exempt from state laws.
States don't decide federal policy, and you knew that when you asked the question.
I don't think that we have had the court case of a state telling a Marine General that his marriage is illegal in that state yet, unless the state laws against black and white marriage are looked at.
Remember that abortion and gay marriage in the military and for federal employees, and in immigration, and homosexuals in the military, are all federal.
We need to select candidates who are against liberalism at all levels, from city hall to the state, to the Senate and Presidency, whether negotiating with a County union, or state legislation on gay marriage or abortion, or marriage recognition and abortion in the military, and not let them exist as leaders who support the left’s causes, by pretending that they are forced to support the left’s agenda.