Britain's ex-world heavyweight champion Fury meets undefeated German Tom Schwarz in Las Vegas at about 04:00 BST on Sunday, live on BBC Radio 5 Live.
"If they [Team Joshua] want me to go over there [the UK] they've got to give me 50 million dollars".
The fight with Ruiz, which stripped him of three hard-earned title belts, marked Joshua's first loss in his professional boxing career, and only the second time he has ever been knocked out.
Hearn says Ruiz was initially "picked" by them for the fight last weekend, and he wasn't the "Mandatory" to Joshua.
Joshua's stock massively dropped after suffering his first professional defeat to the Mexican-American challenger in NY.
Both men have stated where they would like it to take place, with Hearn claiming Joshua's side will have the final say. What were people seeing?
"If I was a match fit fighter and some fat man comes off drugs and alcohol and done that to me, I'd never look at the sport again", he added.
Joshua's seventh-round stoppage by Ruiz came as a huge surprise as his opponent had been given barely one month's notice for the fight and weighed in at over 20 pounds heavier than the Briton. The result is a blow for the British heavyweight, who had plans to force a fight with either Tyson Fury or Deontay Wilder. "He would break every heart monitor, has probably worn out every treadmill in the gym, smashes the bag, (but) it's all very unimportant. If you put Joshua in with Wilder or Fury in the United States, it wouldnt sell at all. who the f*** is going to pay to see that fight?"
That was after the pair battled to a draw in December in Los Angeles.
"Does Deontay Wilder have anything to bother me? I've texted him five times and he hasn't replied once".