Mueller has advised Trump's lawyers that his office wants to ask Trump (at least) 49 questions:
https://www.nytimes.com/2018/04/30/us/politics/robert-mueller-questions-trump.html
https://www.nytimes.com/2018/04/30/...an Hacking and Influence in the U.S. Election
https://www.nytimes.com/2018/04/30/us/politics/robert-mueller-questions-trump.html
https://www.nytimes.com/2018/04/30/...an Hacking and Influence in the U.S. Election