I'm unsure if they got those numbers from the source, but this
NY Times story says God of War franchise sold more than 51 million units and that Ghost of Tsushima sold more than 5 million. The latter is a solid guess anyway considering the legs (did anyone posted the October PS Store charts ?) and the 5,7M estimated players
here.
As for God of War, we knew the series sold
21,6 million back in June 2012, so that's quite a jump with only God of War Ascension, God of War III Remastered and Boy of War being released since. I guess God of War is definitly in the top 3 of the best selling PS franchise with Gran Turismo and Uncharted ?