There is no typical path for a MT graduate. And typically, there is no ongoing salary, since work as a performer tends to be short period contracts and not ongoing salaries. Many earn money by doing several things. Some balance performance work with survival jobs. No single job is sustainable really because they are not long term jobs.
I cannot give you what percentage of MT grads are supporting themselves entirely by MT work. I can only relate my own kid’s experience but that is just one person. It doesn’t give you an overall outlook but is merely an example. My daughter is 27. She graduated from a BFA in MT program 7 years ago. She has supported herself since her graduation day at age 20 in NYC. All of her jobs have been in theater or music. She has pieced together many jobs over these years. The first four years or so, besides performance jobs, she had “survival” jobs too but ALL of those were in theater and music (and may not be considered “survival” by some people…such as musical directing, teaching in BFA programs, etc.). She no longer can fit in any survival jobs. But she does have a 3-prong career and currently in busy in all three areas (but if one were not to be busy, she’d have the other two, etc.). She performs in musicals, writes/composes musicals, and is a singer/songwriter (pop/jazz/folk/rock/soul). She is not rich but she fully supports herself working in her field. She works VERY hard and all the time. She is on stage in NYC as I type this.
She would say that it takes time to build a career. You can’t judge it the first couple of years out. Things for her have built up over time. Her career is better now than in her first year, etc. She doesn’t audition much. She doesn’t rely on getting cast as the only way to find work in the field, though she is also cast consistently in shows in recent years. She has also turned down work and/or had schedule conflicts But she works every day and night.
PS, she is engaged to another BFA (Acting) graduate.