Legally, I believe it's not considered "gambling" so long as these store vouchers can't be exchanged for cash. In fact, there's a lot of ways that companies are making products that are legally not considered gambling even though they are functionally gambling (more so than Invaded). Look into what a "sweepstakes casino" is, for example.
That said, this crate is totally a cash grab, and the fact that people aren't even buying it tells you that Invaded as a company is probably doomed. I did a crate analysis and you get about $1.50 in vouchers per purchased key.
If you want to accelerate Invaded's inevitable demise and you have vouchers, you should give away your vouchers in the form of ranks as opposed to keys. They won't expire in 60 days and it's more likely that it actually causes someone to not spend money they would've otherwise spent, as opposed to buying more keys to chase their losses or repeat their wins.