How does Joe react when the prisoner says he stole the pie? What does this reveal about Joe as a person?

He tells the convict he was welcome to the food..... that he'd not see anyone starve. Joe is a good, generous, and honorable man.

"God knows you're welcome to it - so far as it was ever mine," returned Joe, with a saving remembrance of Mrs. Joe. "We don't know what you have done, but we wouldn't have you starved to death for it, poor miserable fellow-creatur. - Would us, Pip?"