While we weren’t necessarily expecting a lot of actors from the proper X-men franchise to appear in New Mutants, seeing James McAvoy play Professor Xavier seemed like a safe bet.
This source would appear to be definitive, so the safe money is on a lack of Professor X.
The odds seemed even greater when Anya Taylor-Joy make a comment that, as she understood it, James McAvoy was going to be in the movie.
At the time we assumed she had some inside information, but perhaps she really didn’t know.