The Brazil-born midfielder underwent a medical at Castel Volturno on Saturday morning but has yet to agree terms with the Partenopei.
"We all know that Jorginho is here but we must still wait to finalize his contract," Benitez explained at a press conference on Saturday. "We need a little more time to do so. He will not be available for Bologna-Napoli [on Sunday afternoon]. But Jorginho is useful for both the present and future and knows Italian football.
"But it is not easy to find other reinforcements. Finding the best of the ones currently available is difficult. It is also imperative to remain within the financial parameters of the club and not to squander money."
Napoli currently sits third in Serie A, 10 points behind league leader Juventus.