Giancarlo Esposito’s tease about the character’s past may indicate he does know some things about the character, or he may just be going off the same information presented to the audience.
In either case, the amount of backstory he gave the character has me optimistic that Vince Gilligan will one day revisit this man and his origins, though, given the events of Breaking Bad, it would have to be a prequel.
Past information from Breaking Bad alleged Gus Fring was a Chilean general under General Augusto Pinochet, but records from his time living there were scrubbed and couldn’t be found by the DEA.