This is what he actually said:
“Jay Z wasn’t great when 2pac and Biggie was alive,” Future said. “It was Biggie, Tupac, Ice Cube. [Reasonable Doubt] wasn’t hot until [Tupac and Biggie] died.”
This is like saying that the moon didn't come out until the sun had gone down. Pac died in 96. Reasonable Doubt dropped in 96. Biggie died in 97. WHHHHYYY the fuck would Jay be the king of Hip hop in the mid-90s before he had even dropped his first album? Nigga Reasonable Doubt wasn't hot until Pac died because Reasonable Doubt didn't exist until after Pac died and Biggie died soon thereafter.
And then there's this
“I’m saying at that time, [it wasn’t hot]. They always go back for your classic album. When Nas dropped his first album, it was great then,” Future explained. “When I Ruled The World came out, it was the best then. You have to go back
Like someone already said, If I Ruled The World wasn't on Illmatic and Illmatic wasn't an overwhelmingly commercial success when it was released.
I'm going to assume this stupidity is because Future is hoping that 15 years from now people will revise his own history to make him seem better than he actually is. But that won't happen because he is not lyrically inclined enough to be considered one of the greatest EMCEES of all time. All the mixtapes in the world won't change that.