Yes, you can cancel his ticket and you'll get a credit for it, but it can only be used by your husband and must be used within one year of the day you booked the flight you are canceling. If you're not 100% certain about him going or not going on the trip there's no need to cancel it now, you can wait until 10 minutes before the flight, although I would suggest not waiting quite that long. Once you do know what his plans are you can cancel if necessary.
