you can get stronger but gaining actual muscle mass takes years and years. 1-2 pounds a year is a realistic goal
and if you want to argue this then prove it mother fucker. there is a reason most people who get gym memberships end up quitting, they realize how hard it is to gain muscle quickly. this is a marathon, not a sprint ... and it never ends. i started lifting weights at 15 and am still battling 25 years later
It's pretty much impossible to tell how much lean muscle mass a given individual can gain in a year when everything is optimized but to give a very rough estimation I would say in best case scenario anywhere between 10 to maybe even 15 pounds.
Too many variables. If you are new to lifting and then hit it hard you will gain a lot more than someone who is natural but has been banging away at the weights for years consistently.