السلام عليكم ورحمة الله وبركاته The khatib of a small masjid asked if I wanted to do khutbah for jumu'ah. How do I know if I am eligible for it? I feel that my 'ilm is extremely tiny and that it's too early, but I am unsure. It could be that I'm trying to be humble. How much 'ilm is required?

You do not have to be a scholar. Shaykh Ibn Baz raḥimahullāh said the khatib does not have to be the most knowledgeable or a scholar, and that if he delivers the khutbah well, even reading it from a sheet, it suffices, as long as he is known for uprightness. Read from a reliable book of khutbahs written by the scholars, and speak only on what you know.