Based on things I've heard from sources I trust just within the last 24 hours, here's what I can say about Abrams and THE LAST JEDI -- he was not creatively involved in THE LAST JEDI in any capacity. He was given a ceremonial producer credit, but he had no input.
He was also, despite public statements suggesting otherwise, extremely interested in doing VIII and IX (the entire trilogy) but THE FORCE AWAKENS was a difficult production behind the scenes, he and Kennedy didn't particularly get along, and Lucasfilm made it clear that unless Abrams was willing to get VIII in theaters by May of 2017 (which was the original release date at the time), they were moving on. Which they did.
Rian Johnson started working on THE LAST JEDI script based only on having read the shooting draft of THE FORCE AWAKENS; he and Abrams did not speak until well after TFA was released and TLJ was deep into preproduction. Abrams' attitude at that point was apparently, "Well, it's your thing now," and he didn't really provide Johnson with notes, nor did he offer what he and Kasdan had been attempting to set up in TFA. Being a good soldier, he praised TLJ's script publicly.