I will appreciate if someone could shed more light here, in particular which composers have had an influence on Mozart's work?
Mozart's father, Leopold, was obviously an early influence on the young Wolfgang as his teacher.
JC Bach was a big influence on Mozart. Stanley Sadie in Mozart: The Early Years said of JC Bach (in relation to Mozart): "Few composers, Leopold Mozart apart, exercised a comparable influence on the boy or indeed the man."
See http://www.biu.ac.il/hu/mu/min-ad/06-2/8_Bach-Mozart89-104.pdf for a detailed essay on the JC Bach / WA Mozart connection.
Haydn and Mozart had a mutual influence on each other (see http://en.wikipedia.org/wiki/Haydn_and_Mozart)