Yes, a gift affidavit needs to be notarized to ensure its legitimacy. Notaries are legally required to verify the identity of any person who signs a document. They also must certify that all parties signing the document were present during the signing process. This helps prevent fraud because it ensures that no one has forged any signatures on the document.
In addition, if there are any questions about authenticity later (for example, if someone claims someone else signed for them without their knowledge), it can be shown that all parties were present during the signing process and that nobody was coerced into signing anything against their wishes.