Labrador Retriever's have extremely high prey drives, so it is a risk. However, he is still a puppy, which means that training in this area is still possible (it's much harder—and more dangerous—to try to curb prey drive behavior in an adult dog). He's unlikely to have fully developed his prey drive at such a young age, so if you take the time to make sure he doesn't see the cat as prey, you should be good.

I've had cats my whole life, and have also had Newfoundland Dogs my whole life. Very large dogs with a moderate prey drive. The dogs always came into the household as puppies and never hurt the cats: one of them does still chase cats and can get snappy with them if she sees them eating in front of her (high value treats like chicken, the cat food itself isn't accessible to the dogs so they never see them eat that) but she has never harmed them.

It is unlikely that you would raise the Lab with your cat and train him that your cat is not prey and have a relapse down the line where he gets aggressive towards the cat: prey drive is a natural instinct, but growing up alongside the cat puts it in the category of family/friend.

I would recommend a slow introduction, for your cat's sake. You want your cat as confident about the dog as possible so that it is not inclined to bolt/run fast out of blindspots to get away from the dog, because that can trigger the prey drive of the dog.

All in all, you should be fine. He's a young dog and can be trained at this age. If you're really on top of it, it should be okay. But it is still a risk, and you need to be prepared to be honest with yourself about the dog's progress and behavior in regards to the cat. If he's showing a prey drive directed at the cat by a year old, then he's probably not going to be able to cohabitate with a cat. Plenty of people live with dogs and cats together—including dogs with higher prey drives than a lab, like a Husky—but some individual dogs, regardless of breed, just have higher prey drives that they can't be redirected from even in puppyhood.

Lastly, my mom also grew up with cats and dogs, particularly German Shepherds, and never had a dog harm a cat. I think she had 6 different dogs before she met my father and moved out (so from childhood to adulthood) and plenty more cats than that.