Who believes tom Robinson has a chance at being set free and why

Jem believes that Tom Robinson will be set free after he listens to Tom's testimony. He is convinced that Tom will be set free because there is no concrete evidence against him, and the testimony of the Ewell's is dubious.

When Tom Robinson is on the stand, much of his testimony contradicts what Bob and Mayella Ewell have claimed. For instance, he testifies that he never came on the property without being asked. But, Tom...

Jem believes that Tom Robinson will be set free after he listens to Tom's testimony. He is convinced that Tom will be set free because there is no concrete evidence against him, and the testimony of the Ewell's is dubious.

When Tom Robinson is on the stand, much of his testimony contradicts what Bob and Mayella Ewell have claimed. For instance, he testifies that he never came on the property without being asked. But, Tom is probably the only person who ever treated Mayella with kindness; he would help her with her chores when he passed her house on his way to and from working for Mr. Deas. Tom explains,

"Mr. Ewell didn't seem to help her none, and neither did the chillun....

Further, he reports what transpired between him and Mayella, and he states that Bob Ewell cursed his daughter when he arrived and witnessed her actions. Above all, Tom's testimony contradicts the confused statements of Mayella and the accusations of Bob Ewell. Furthermore, there is no concrete evidence to prove rape. 

So, in his closing statements, Atticus points out that there is notable variance between the testimony of Bob and Mayella Ewell, there is no medical evidence of rape, and the testimony of the defendant has "flatly contradicted" that of the two supposed witnesses. The only evidence is circumstantial: Mayella was struck, but she was beaten by someone who is left-handed. Furthermore, Tom Robinson has no use of his left arm and hand.

After lunch, Jem is convinced that Atticus has won, and he tells Reverend Sykes,

"...we've won it....Don't see how any jury could convict on what we heard--"

But, Reverend Sykes is not so optimistic:

"Mr. Jem, I ain't ever seen any jury decide in favor of a colored man over a white man..."

Then, when the jury returns, Scout notices something that only a lawyer's child would be aware of its significance: When the jury returns, no one looks at the defendant, and Scout notes, "A jury never looks at a defendant it has convicted."