Here is also my comment from reddit:

after a “small” research from me (about 2 hours), this is what I can say…it’s most likely named “Kampfpanzer 50″ and not “50t” (there were other project names like “Kampfpanzer 70/80/90″) and Germany stopped naming tank projects after their weight limit at the end of WW2, but still, if it means that it was developed in the 50′s…I can say nope…fake tank, the german industry had a research disadvantage in the 50′s, there was only 1 tank which was developed in this decade, the “Indienpanzer” by daimler-benz and that project failed. The tank could also be a pre-series leopard 1 ) although the model looks different), but at the beginning of the development the german army wanted the british 105mm-L7 gun as armament, so an “old school” 105mm gun was not an option since the wehrmacht used only 8,8cm gun or 12,8cm guns during the war (AT guns and tank guns), Porsche wanted a 10,5cm gun or a 15cm gun for the tiger 2, but it was denied, so technically a wehrmacht 10,5 cm KwK was only a blueprint dream.