Is GameCupid Legit

I wouldn't recommend using the website. You can't tag features that other people already tagged, so if a game is fully tagged you'll have to find one that isn't. And from what I can see a lot of games are already fully or almost fully tagged and since you only get 1 coin per tag... it would take ages to get enough for a game (unless you cheat and randomly tag everything but in that case you'll likely going to get banned anyway).

I've read a bit about the website and it doesn't seem like a dating service. It matches YOU with the GAMES that the website thinks you'll like. You basically play games, and it'll use it's recommendation engine to tell you which games fit your style.

Indeed. You have to put tags on games. It seems like you get 1 coin per tag, cheapest game is 500 coins and most expensive one 4,000 coins.

How long did it take to get 4k coins?

Looking at gamecupid right now it's more like Amazon Mechanical Turk cheap data entry jobbies than the "complete these offers" sites, only instead of data entry it's tagging game features (think Steam Tags) for various platforms -- PC, console, mobile... even retro platforms like Amiga are represented.

You tag through a decently designed GUI and your tags are subject to peer review. You have to do a LOT of work to get the cheapest of "bundle" games. You'd probably be better off of working on Mechanical Turk for Amazon money and buy stuff during special sales.

In conclusion, this doesn't seem like a scam in the classic sense of the word. "Cheap child labour" is more like it :)