I would start by asking your husband why he used your SSN at a casino. And then get the casino to issue a corrected W-2G.
if your filing jointly it makes no difference. If something is awry in your marriage you would be able to claim innocent spouse but the IRS might assert it's your income because of your SSN, not spouse's. it might also make a difference for state income taxes, but can't be sure. Ask your spouse why it was done.