Ranieri admits he tried to sign the stopper while in charge of Leicester City.
"I think the world of Gaston, I wanted him when I was at Leicester. I'm sure he'll give us a big hand," he said.
"The lads are regaining confidence but we must continue in this way, so as not to throw away our good work."
Samp meet Atalanta today and Ranieri added: "Our next opponents are very strong. Ilicic is a champion, as is Muriel, but in general [Gian Piero] Gasperini's squad has been built very well and has played together for years. It'll take a good performance to beat them."