This isn't something we're able to assume, you'd have to get it to a repair shop or open the PS3 System yourself and look where the leakage came then perhaps try to clean it up.
Coffee is better than Soda, soda is sticky as shit.
I had coffee on my computer, and on my other computer Soda. The soda one died for a year then started working again, coffee one started working asap. Though, this is a PS3 so hmm, i wouldnt think the coffee would be able to come inside the ps3 itself