In the types I've been involved with I've never seen a method of measuring density within the aircraft. Tiny planes to big ones. I could understand tank farms and trucks using a capacitive indication system in conjunction with a density measurement to establish accurate volume or specific gravity for distribution for use.
Upon further reading, I guess some fancy aircraft do use fuel temp probes to correct for density. I didn't think capacitance probes would be effected by it. Guess they can be affected.