To answer your question, Yes, there is a line waiting to get in.
It usually forms at 08:30am going all the way back to the ticket booth.
When you are at the front of the line, it means you can enter the park ahead of everyone else and go for front seat rides on the coasters. They don't have a rope drop like they do at Disney. When you go thru the turnstile, you're in, and can do all the rides in Marvel Island. Sometimes during non busy times they rope off the entrances to the Lost Continent and Toon Lagoon until 10am, but you can still ride the big 3 (Hulk, Dr. Doom, Spiderman) in Marvel.
The walk from the parking garage to the gate is about 15 minutes. So right after you show up, a long line will form behind you.