Aw, poor lad...what a start to life. Good job he found you
Hand feeding is definitely one of the best ways to make friends with a shy Chinese. As racinghamster says, they soon learn where the treats come from. I can now just say 'want a treat?' to my two girls, and they go and stand underneath the cage door & wait for it to be presented!
I've also found a snuggle pouch helps. Let them hop into the pouch, then place it on your lap and let them come out in their own time & explore. Giving them somewhere safe to run back to seems to calm them down (and a bit of their favourite treat helps encourage them to explore...)
I find Chinese to be less demanding of your attention than other species (mine usually only want to come out about twice a week) but once out they are nosy & playful hams that love to find somewhere comfortable to snuggle up. I'm sure Eric will soon become more confident & easier to handle. Just takes a little time...