Not getting Gates out early is a big problem, which can be mitigated by playing a 50 card deck and putting in searches like King Solomon, King Hiram, King Ahab, Table of Demons, Zaccheus, etc. It's tough to fit a Gates defense into a 50 card deck though.
Honestly, the biggest problem might be the lack of speed. Samaria sites + a slow defense just slogs the deck. The new King Jeroboam II can help, but his ability can be both prevented and interrupted. Wickedness Abounds could definitely help. And a fast offense with some of the searches above (Purple is a good choice) is very helpful.