Can you replace a 25v 500uf capacitor with 25v 470uf capacitor?

It will depend on the application. If you are trying to rapair some thing which as per design needs 470uF capacitor but you only have 100uF capacitors available., you can put 5 of these in parallel if possible (if SMD you can put one on top of another and solder). That will give you a total of 500uF close to the original value.

- Neeraj Sharma