Your 'tiel is so cute! Looks like a normal grey to me, his/her back looks cinnamon but I think that's just the lighting in the photos as the tail and wing feathers are definitely grey.
For normal greys gender can't be visually determined until your 'tiel has molted, but since it's impossible to guess at the age, I can't tell you the sex as there's no way to know if he/she has molted yet or not.
Also... Is this just a temporary cage and perch? I would recommend getting some other perches that are more comfortable for his/her feet, like natural wood perches, branches from safe trees, or a calcium perch.
Thank you for your message, i was aiming at the possibility of Pastelface or yellowcheek. I guess we gonna have to wait and see .
As for the cage, it's just temporary (quarantine) before putting it with other birds ied:
Even experts have a hard time telling these mutations apart sometimes, and I'm not an expert. But your best bet is to join the National Cockatiel Society's Facebook group, post some good pictures there, and ask for opinions.
Personally I lean toward yellowcheek, but like I said I'm not an expert, and I might think differently if I saw a different picture. There are two yellowcheek mutations and I don't know how to tell them apart visually. But for what it's worth, sex-linked yellowcheek is hard to breed and dominant yellowcheek isn't a problem, so DYC is more likely than SLYC.
I agree it looks to have very light cheek patches so could be a cheek patch mutation. As this bird is not pied I would attempt wing spot sexing. Open up the wing and look at the under side. If there are spots on all the flight feathers you have a girl, if the spots go along the primary flights and not the secondary then you have a boy. This will work as the baby hasn’t started moulting yet. Susan Russo has some good pictures on her website justcockatiels.com I strongly recommend her website to anyone with cockatiels. Full of lots of information on every topic you can think of!