The complaints (listed in the tweet thread) has comparison shots and it's... 
(Image removed from quote.)
He's not the "antagonist" at all in the show. He's the brother of the grieving mother, and is trying to help her.
Since i'm probably the only one on the Bore who watched Servant (which i loved, probably my show of the year) i'll say that from reading the pdf, the premise sounds very close, even though reborn dolls to cope with trauma are a thing, i could see them watching the movie and starting from that premise.
Both movie and show operating in the same horror/thriller genre probably doesn't help (though again, a girl coming down a dark stairway is hardly a unique idea).
However in the complaint itself they lament many points in which the show veers fundamentally from the premise and themes of the movie, as a way to indicate how they appropriated and bastardized the material, but to me could just as easily mean, that they had no intention of telling the same story.
A larger element of the show seems to be a mythology (so far only hinted at) about some sort of religious group, behind the nanny, which would further separate them.
That said, i see some of the similarities as rather suspect, and the premise itself is quite specific especially within the same genre.
I'm not gonna comment on M.Night's character 'cause i don't know the guy, and internet gossip is distinguished mentally-challenged fellowed, but with so many on GAF convinced Bloodborne invented gothic architecture, i'll admit i always tend to take these plagiarism claims with a grain of salt.
EDIT: Suffice to say, if they
did copy from the movie, they should pay through the nose for it, and make her rich.
