I chose Jonas as my topic for The Giver. But I need a thesis statement about Jonas and his emotions, memories, and other stuff.

Because Jonas is the main character of the novel, he is a perfect topic for your essay. However, without knowing what your assignment asks for OR what your own argument is about Jonas, it is difficult to suggest a specific thesis.

You said you wanted to talk about his emotions, memories, and "other stuff." Since "other stuff" is vague and could mean anything, I'll talk about how you could tie together emotions and memories and...

Because Jonas is the main character of the novel, he is a perfect topic for your essay. However, without knowing what your assignment asks for OR what your own argument is about Jonas, it is difficult to suggest a specific thesis.

You said you wanted to talk about his emotions, memories, and "other stuff." Since "other stuff" is vague and could mean anything, I'll talk about how you could tie together emotions and memories and give you a sample thesis. It is up to you to make sure that argument would work for your particular assignment.

Jonas has fairly superficial emotions through the first part of the book until he begins to receive memories from the Giver. At that point, he begins to experience emotions that are more complex and different that the emotions of those around him. For example, he understands what emotional pain is after remembering being at war and not being able to save someone. These are feelings that other people in the community have no concept of and that causes Jonas to begin to feel isolated. In turn, he begins to become resentful and even angry about the superficial feelings everyone in the community appears to have and we see this when his family is sharing their feelings about their days. His sister expresses anger, but Jonas realizes it is not really anger, but mere impatience. 

Perhaps you could tie the emotions and the memories together in your thesis. It might look something like this: Jonas experiences emotional growth as a result of the memories he receives from the Giver, but that same emotional growth also causes him to feel anxious and angry.