I read Maynards biography on Beethoven awhile ago, and there was one composer I meant to check out who he said influenced Beethoven- particularly his 5th symphony. The first name (I think) was Gustav, and the initial of his last name was M.
I believe the book said it was Schumann who pointed out similarities between Beethoven's 5th and a work by Gustav M.
No, it wasn't Mahler. It was Etienne Nicolas Mehul. I have the book, and the reference is on page 180. Mahler was born 30 years after Beethoven died, making it very difficult for him to influence Beethoven at all.
Schumann said that there were similarities between Mehul's symphony in g minor and Beethoven's 5th.