If this report is true, then Mueller will asking to interview Trump soon on what he knows about the dismissal of both Flynn and Comey:
WAPO – Special counsel Robert S. Mueller III is seeking to question President Trump in the coming weeks about his decisions to oust national security adviser Michael Flynn and FBI Director James B. Comey, according to two people familiar with his plans.
Mueller’s interest in the events that led Trump to push out Flynn and Comey indicates that his investigation is intensifying its focus on possible efforts by the president or others to obstruct or blunt the special counsel’s probe.
Trump’s attorneys have crafted some negotiating terms for the president’s interview with Mueller’s team, one that could be presented to the special counsel as soon as next week, according to the two people.
The president’s legal team hopes to provide Trump’s testimony in a hybrid form — answering some questions in a face-to-face interview and others in a written statement.
It’s also been reported today that Mueller has already interviewed Comey on his dismissal and Sessions on the Russia investigation. Apart from that we really don’t know anything about those interviews.