I sent btc to a gemz wallet? is the the btc lost?

I stupidly sent btc to gemz address wallet on the exchange im using. Its sat confirming on the blockchain but I cant obviously access it.

If you sent it to the exchange, then you most likely don’t have the private key for that address.
There’s been cases like this before. Basically you need to contact the exchange and tell them that and after a lot of hassle (they will need to apply for weird procedure internally) they may be able to send you BTC back.
Technically it’s easy, but as you can imagine to manually fiddle around with those addresses and use the private key is a big inconvenience so it’s never fast. But in both Polo and BTer before they used to help people with that.