Seems to have been a bit of confusion in several directions here, but just to clarify: in modern usage 金子 is read only as Kaneko, and is a very common surname. The "kinsu" reading is archaic; a typical native speaker may never have heard of it.
That one sounds like Chinese word with hallucinated Japanese usage. 子 is IIUC casually used to mean "little ___ things" in Chinese, but same isn't the case with Japanese; 金子 is used as a somewhat discrete way to refer to an envelope of cash.
お金 : okane : money
金曜日 : kinyoubi : Friday (shortened to 金 on some calendars, kind of like how we do “Fri” sometimes in English)
金子 : kaneko : gold coin
金魚 : kingyo : goldfish