The SVT look so similar to an AK 47. Has the Ak 47 been developed by the same guys? And can the AK 47 be called an predecessor of the AK 47?
The SVT-38 and -40 were developed by Tokarev. The rifle that came before it, the AVS-36, was a hunk of junk developed by Simonov. The SKS was based off the AVS-36, and it came out in 1945 and actually saw action in Berlin.
The AK-47 and the STG-44 are completely different. The only design element they share is the long stroke gas piston. The STG uses a stamped, enclosed upper receiver, a tilting bolt, a removable trigger group, and a slide-in magazine well (it actually has quite a few design elements in common with the G3 and CETME rifles, which were based on the STG-45). The AK-47 uses a machined (later stamped with the AKM in 1963) receiver, a rotating bolt, a receiver cover, a built in trigger group, and a rock-in style magazine well.
As you can see, they are completely different. However, they were developed only a few years apart. There is a rifle based largely on the STG-44 though; the Czech VZ.58.