Details about this event are scarce. It will take place in the USA and was rumoured to take place in February 2019, but KSI confirmed that this would not happen (due to Logan's management team taking their time to decide on location/legality issues etc.).
Immediately after the result of the first fight in 2018 - which ended in a draw - a rematch was agreed to live in the ring. In the days following the fight, KSI suggested the match take place in May 2019 but Logan wanted it to take place in December 2018. A date in the middle (February 2019) was suggested, however this was later confirmed to also be false.
The fight will definately take place in the United States. KSI has stated numerous times that he hopes the venue will be located on the East Coast, since that makes the most sense timezone-wise (if it took place on the West Coast, it would be the middle of the night for the UK audience).