When we brought Maggie home at 8 weeks old, I had a couple of sets of steps that would allow her access to the furniture and bed without her having to jump down off of the furniture onto the floor. In my humble opinion, the impact of jumping down puts stress not only on their knees & hips, but also their back. Maggie is pretty faithful about using the steps, unless she is super excited about something then she will jump down......I don't really mind an occassional jump; at least she's not jumping down all of the time.
Take it easy for now, muscles and tendons do not grow at the same rate as bone structure. When this happens, if the puppy is jumping or playing too hard , permanent damage can occur.
I just looked at your profile, and your dog is over two which means his skeleton is fully mature. It all depends on the dog and the furniture. If you look at a healthily proportioned Corgi, you will see that it is actually a medium sized dogs with short legs, more so than a true long-backed breed.
I let the dog jump on and off the couch, but he isn't tearing around playing that way, which I would discourage. He hops on and off occasionally to snooze, and his body is so long that he is nearly stepping down rather than leaping.
I would avoid having him jump on and off a bed with a box spring, as that is quite tall. But I would not let any dog make that high a jump, not just a Corgi. We solve that problem by not allowing the dog in the bedroom; that's the cat's domain. :-)
If your dog is overweight, jumping down of course could put strain on his front legs. You need to take reasonable precautions with a Corgi, but their backs don't seem to be as fragile as, say, dachshunds.