MacAnthony sold Gayle to Palace this week.
"He could probably make Palace £20million in the next 24 months," he told talkSPORT.
"He is international quality for me. The kid is 22. He could be anything. His technical ability is unbelievable.
"I have never seen a striker hit the target [as much as him]. He has something like a 72 per cent on target ratio, which is unbelievable for a striker.
"He is the real deal. I am now a Crystal Palace fan for the next three years. I hope they go out and buy more players and do really well because, if they feed this boy, he will go out and score 20 league goals a season.
"People are saying we have had Palace's pants down, but they have got an unbelievable acquisition that can only be worth millions more to them. If he keeps them in the Premier League, they will be laughing all the way to the bank.