If you live in Russia or some other place where Sibirians are common, so shure, he could be a mix with a near Sibirian Ancestor.
But I wouldnt spontaneously call him for an Sibirian mix... A very nice domestic tabby. Probably medium hair, but perhaps a short hair with a longish fur. (yes I saw the tail pic on your other thread). One of those where it may be difficult to be sure.
Google on Masha from Obninsk - the hero cat - (possibly a saint if you ask me). she is an natural sibirian, very typical.