You’re never too old to start learning, and age is not a factor in making a game or working for a developer at any position, so don’t worry about that. As with most companies, it will be guys in their mid/late 30’s and up in more senior positions, with younger people taking the junior positions.
That said, if you already have a career on the go that isn’t directly relevant to game development and you want to join a studio, you will need to consider the impact of restarting your career from scratch. Video game developers often have relatively low pay at the more junior levels, particularly in the art department. If you’re planning to join a developer you may need to take into consideration a pay cut.
This is a problem I and some friends of mine have, as the salary I earn in my current job is going to be significantly higher than anything I’ll get as a junior programmer at a studio (which is what I will be without any significant professional programming experience). With a family and a mortgage it’s just not possible to take that kind of hit. You may not have that same problem, so if not good luck!