I doubt it. He might be influenced, but there were a lot of differences between them. He left no manifestos, he had girlfriend(s), successes in schools and universities. He probably didn't want to accept his mental illness, stopped taking medications, plunged into depression. He was getting darker and darker as a person, and decided to execute his "escape from the world plan". He was in need of attention, that's why he choose university stage as the crime place.
I don't deny he was influenced by the Columbine and other mass shootings - I just don't think it was that simple, as he was copycating. In my opinion he had more darker and personal motives to do this. But we'll never know what were they exactly.