It depends on your belief system. Both are 'demons' but in different systems.
All religions have demons of some sort, most are personified.
He did not. Christians created the devil, game designers created Dahak.
There is no Dahak!
No. Dahak is a pretend character in a video game.
If Dahak, who is a fictional character, did indeed have a child called Adolf Hitler, then yes, Adolf Hitler would have been fake, but since Dahak is fake and never had a child called Adolf Hitler, Adolf Hitler could not be fake, since Adolf Hitler really existed, therefore the only conclusion that can be drawn is that Dahak is a fictional character which does not exist in real life, but Adolf Hitler is not Dahak's child and therefore Adolf Hitler existed and is not fake.
No
No.
Dahak is a pretend evil god in a video game.
No, he would be the son of the devil. As Zahhak (Dahak) was the son of Angra Mainyu which was the devil in Zoroastrianism.
No
No.
No.
No.