OK so I think I'm looking at the rules right but I wanted conformation. If I slap Gonti into a mimic vat and pop out a token of him I get his ETB trigger and exile one of the top 4 cards. Now end of turn Gonti's token gets exiled by mimic vat. I can cast any of the cards I exile with Gonti tokens from mimic vat at any time even when Gonti isn't around?
yes. the only thing that would stop Gonti, lord of luxury's ability is if the card somehow came out of exile before you cast it. Because the last lil' bit of his text is "For as long as that card remains exiled...etc".
Gonti, Lord of Luxury and Mimic Vat