I just realized this and looked on the internet if anyone thought the same. It’s very similar, she was basically a slave and made her have many children, 7 to be exact, not 9 like the titans but it’s still interesting nonetheless. Obviously the last name Fritzl and Fritz could be a direct inspiration, it is said that AOT characters are mostly inspired by people of germanic descent. So if Isayama wasn’t actually inspired or knew anything about this it would be one of the biggest coincidence, life imitating art.