Can a ps2 rfu cable fit the ps3?

May be...

I want to buy a ps3 but my TV is old and does not have AV holes. I wanted to know if the ps2 RFU adapter also works on the ps3 so I can buy one and use it until I get an HD TV

if this is what you have, http://www.comet.co.uk/comet/dyn_imgs/pr...

then it should work because ps3 uses the same kind of plug the ps2 uses.

Yes, the PS2 and PS3 use the same multi-AV connector, so you can use any PS2 cable on the PS3.