Good outlook! Grips are genetic, but they mostly matter for sport. You can do a lot to make your dog love to tug, and improve his grips.
Some dogs have better grips or show more interest in different types of tugs. There are jute tugs, soft fleece tugs, big wide bite pillows and small narrow tugs- even bite rags. Try to find a tug that your dog really likes the feel of biting, that will help.
One trick I like that works for me to build good grips and drive for the tug is using a long line. I'll get a good game of tug going and make sure I've got a nice full grip from the dog, and then let her have it. Then, keeping her moving the whole time, I'll run her in a circle around me on the long line- the dog will be proud, tail up, happy body language- because she "won" the toy. After a few circles, I'll call in her, and play tug again. I find this makes the dog feel more secure and get a good understanding of the game of tug, while not having an opportunity to run off with the tug toy and just hang out possessing it by herself. Also, it builds engagement with me as the handler and stresses the fact that playing tug with me is the best prize.
Hope some of this helps!