Theoretically, an AK47 mag can fit in an AK74, but of course would not chamber the round, whereas an AK74 mag won't fit into an AK47 because the 74 magazine has a little bit up on the top of it specifically to prevent it seating in an AK47, because an AK74 round would chamber into an AK47, so they added that feature to prevent it from being done by accident. But that's in the world of the real weapons. In Stalker, it's probably just a visual error by a 3D modelling artist who thinks all AKs are cross compatible in the same way that a lot of people think that Krinkov is some kind of official designation as opposed to the truth of it being a nickname of dubious origins supposedly deriving from the Afghan war if you believe the story about it.
Of course with airsoft guns it makes no difference because the calibre is always 6mm (except on those weird and rare 8mm calibre airsoft guns). So I'm guessing it probably would fit, but having said that, of all the airsoft AKs I've got, I know that some of them have magazines which, whilst they do fit into other AKs, don't feed the BBs too well. I should imagine most airsoft AKs of the same brand would play ball, but I wouldn't put money on it working across different manufacturers, and of course it's worth noting that some airsoft guns are branded under one name, but actually made by other companies, so the brand itself is no guarantee of commonality. I'd try it with someone else's gun at a skirmish rather than spending money on it and finding out that it doesn't the hard way. That said, mags are fairly easy to modify and with AKs, they all tend to lock in via the same mechanism, so providing the feed hole lines up correctly, I bet you could get most of them to work, and even if it didn't, you could indulge in a little surgery and make it so.
