幾 for how many. 几 stays 几 for a small table.
几 is a picture of a small table or stool — two legs and a top. (You'll still see it meaning 'small table' in 茶几, a tea table.) It was borrowed for the question 'how many' (jǐ), usually for small numbers under ten.
几 asks 'how many' when you expect a small number: 几个? (How many?), 几岁? (How old? — for kids), 几点? (What time? — 'how many o'clock'). It also means 'a few': 几天 (a few days), 几个人 (a few people). For likely-large numbers, Chinese uses 多少 (which you already know) instead.
A little two-legged table — borrowed to ask HOW MANY (a small number).
几 asks about small counts (几个 = how many), 多少 about large ones (多少钱 = how much money). Chinese picks the question word by the expected size of the answer.