Will my 5 week german shepherd get along with my 13 year old german shepherd?

yes he should. Also let the dogs meet not in the house but somewhere where the older dog has never been. other wise the older dog will think the youngest dog is on his territory and the oldest dog might bite. Then walk them home and see how the older dog acts when the youngest dog enters your home. If he the older dog bite him hit the older dog on the nose just hard enough to make it hurt him.