I think you might be overestimating how much writers are concerned by how they are influenced by the work of others, and yet they can still be highly-protective of a specific version of a story they happened to have produced themselves.
Harlan Ellison sued James Cameron over Terminator, yet Ellison also dismissively points out that the basis of his own tv show was taken from a Robert Heinlein novel (although he erroneously identifies it as a Harry Harrison) in this rather lengthy dissection of the car crash that was The Star Lost and how it was just a mish-mash of other things. I would recommend the bit starting around 13.30 or so for Ellison being quite unabashed about what derivative horseshit he knew was turning in, but he was still clearly possessive of it until he angrily rage-quit the whole enterprise.
James Cameron vehemently denies having even seen, let alone copied, Harlan Ellison's episode of The Outer Limits, Soldier. Having seen the episode, I tend to side with Cameron; they bear little similarity.
The Terminator does bear huge similarities to an X-Men story, Days Of Future Past. And Cameron is an admitted fan of the X-Men, and was at one point in the nineties set to direct an X-Men film.
And to muddy the matters more, John Byrne, who plotted and drew the X-Men story Days Of Future Past has since admitted that he lifted the plot from a Dr Who episode, Day Of The Daleks (if you ever see this episode, made in 1972, it bears a shocking resemblance in both story and tone, to The Terminator, far more so than Ellison's Soldier).