Do you think Eladio was aware about Gus' intention to kill him and the entire Cartel? I mean, he said to Gus in "Fun and Games" that he could see the hate in his eyes.
I think Eladio somehow knew Gus wanted revenge but kept doing business with the chicken man because he makes them earn a lot of money and underestimated that hatred Gus always had. Anyone with common sense would at the very least suspect that someone who works with you even after killing his partner in front of his eyes would seek for revenge
I don't believe Eladio was stupid enough to not see that. He probably believed he "tamed" Fring and understood the message he gave to him back then in 1989