It takes a minimum of two years to be airline eligible, sometimes longer. So let’s say you start today, that makes you 53 at the very earliest. Airline pilots must retire by their 65th birthday, so you do have some time left. In today’s environment, it is realistic to assume that you could get hired at a regional airline, assuming you are attractive to them. You do not have enough time to make it to a major airline.
Now there is absolutely nothing wrong with working at a regional airline, you can make good money there and have a good quality of life.
Just to be sure though, I would recommend that you contact the recruiting departments of several regional airlines and ask them about your age.