Viola is campaigning in supporting and she is going to win. Her performance is flawless
(For the record, the reason she refused to go supporting for "The Help" was because there were no other black women who had a real shot at Lead Actress that year. And she wanted there to be at least one person of color in the lead category. This year, even w/o her in lead Ruth Negga is likely to be nominated there, and Taraji P Henson has an outside shot. So its unlikely to be an all white category).
As for Kushner and the screenplay, there isn't much "work" to speak of. There are maybe 5 lines of added dialogue (mostly for quick 5 second scenes outside the house) but the rest is just the Wilson play. There has been a rumor that Kushner helped with the script structure, but he is only credited as a producer. So even if the rumor did hold true, the amount of work he supposedly put in would be minimal, basically that of a script doctor who would go uncredited anyway.