Should this say 5 - 6 pieces of chicken instead of 56 pieces?

One way to figure the recipe is by weight or volume per person. A boneless chicken thigh has about 3 oz meat, and many recipes recommend one per child or light eater, two per adult or bigger eater.
Get as much as needed for your six people you're serving, cut in pieces to fry and complete the recipe.

Good question, there. It's a little odd the way it's written to say for sure. The recipe is meant to serve 3-4 people, and it says the pieces should be cut bitesize. 56 bite size bits of chicken works out to about 12 pieces per person, give or take a few. I think that would only require maybe 4 boneless chicken thighs at most to obtain. 5-6 boneless chicken thighs would give you a LOT of chicken bits. Not that I think anyone would complain, but still. At any rate, use your discretion here and the amount of chicken you think most judicious.