Firstly, you have failed to look at the times frames involved. <PERSON> killed <PERSON> on the 14th of February 2013.
Gone Girl was in the works a long time before the murder
"Gone Girl is a film adaptation of <PERSON>'s 2012 novel of the same name, and the author also wrote the adapted screenplay. One of the film's producers, <PERSON>, read the manuscript of the novel in 2011 and brought it to the attention of <PERSON> in December of that year. <PERSON> and <PERSON> then collaborated with <PERSON> to further develop the manuscript—with <PERSON>'s film agent, <PERSON>, they met with film studios in early 2012.[6]
<PERSON> submitted her first draft screenplay to 20th Century Fox in December 2012, before <PERSON> was selected as the director for the project."
So if the first draft of the screenplay was submitted 3 months the prior to <PERSON> killing <PERSON>, and the screenplay was based on the book, I find it highly unlikely that they would have decided to change the screenplay and let it be affected or influenced by a murder which would only be tried in court after the movie was filmed.
Secondly, <PERSON> started filming in Sept 2013 for about 5 weeks. The details of <PERSON>'s murder were not fully explored until the trial started in March 2014. 918
It was live coverage of the trial which pushed the story into worldwide media exposure.
Third: The murder of <PERSON> is by no means unique and there are many other cases that spring to mind like the <PERSON> and <PERSON> trials. Regardless of how long ago these famous trials and murders occurred, their themes still play out in popular culture and daily references. Any murder of a girlfriend or spouse with a public figure involved is going to play out in the media in the same way. All famous trials are going to resonate in some ways.
You have to ask <PERSON> to give you an absolute answer, but my conclusion is it is highly unlikely that he would have seen the need to make the movie resonate with the Oscar Trial. Or to use your words, I doubt he needed to or was influenced to 'play up' any thematic similarities.
And before you ask this question in the future years to come: no, I don't think the director of the one day to be made <PERSON> biopic will be influenced into introducing thematic similarities from Gone Girl. 918