According to the YouTube Creators twitter account, YouTube has ‘temporarily suspended ads’ on Logan Paul’s channel. You can see the statement here:
In response to Logan Paul’s recent pattern of behavior, we’ve temporarily suspended ads on his channels.
— YouTube Creators (@YTCreators) February 9, 2018
The recent pattern of behaviour started when Paul posted a video situated in the ‘Suicide Forest’ in Japan, and had footage of a deceased man. Even after apologising he has posted more controversial videos recently, that have resulted in many people demanding for him to be reprimanded, and YouTube policy enforced and changed to prevent this kind of content reaching his millions of young fans.