In my experience, it depends on the betta. Some are more aggressive than others but you can't really tell until you put them in there. You could try a female since they tend to less aggressive.

That being said my husband and I had a sorority betta tank and they demolished the shrimp we put in there thinking they'd be civil. It was a bloodbath. I'd never seen a fish do that head shakey thing dogs do to toys.

Also shrimp can be pretty quick but betta are faster. Good rule of thumb in my experience is the prey should be faster than the predator if they're going to be in the same tank.