But can he stop him watching Fox and Friends?

So, John Kelly recognizes the problem, but I have my doubts he can solve it:

When new White House chief of staff John Kelly huddled with senior staff on his first day at work, he outlined a key problem in President Donald Trump’s White House that he planned to fix: Bad information getting into the president’s hands.

Kelly told the staff that information needed to flow through him – whether on paper or in briefings –because the president would make better decisions if given good information.

I like this summary of Trump's bad sources:

In the West Wing, many of the president’s most controversial decisions have been attributed to bad information, partially because the president is easily swayed by the last person he talked to – or the last thing he read.

For example, he accused President Barack Obama of tapping his phone line in Trump Tower after seeing comments from a conservative talk show host and a Breitbart News article. He has often posted some of his most controversial tweets while watching Fox News and stewing. He has sometimes seemed to view television accounts of the news as fact more than information from people armed with classified information. He has made decisions about legal matters or major policy decisions while consulting with some aides – only to reverse them after talking to family members or friends, who he dials late at night.

He has been given information of dubious quality, from stories by GotNews.com, a blog written by a right-wing provocateur named Charles Johnson to segments from segments of debunked documentaries. He has, at times, listened to real estate friends about legislative strategy while ignoring Speaker Paul Ryan or Senate Majority Leader Mitch McConnell.

By limiting information, and making it go through proper channels, Kelly is “ensuring Trump doesn’t make his decisions based on some bullshit he watched at midnight or on Breitbart,” said Chris Whipple, who recently wrote a book on the chief-of-staff role.

I reckon all that will happen is that Hannity or someone like him will turn on Kelly, and tell Trump that he is giving Kelly too much control, and he'll be gone.