Salvio enjoyed an impressive season with the Portuguese giants and was part of the Benfica team beaten in the Europa League final by Chelsea.
Speculation has linked Everton with a move for the Argentina international and agent Agustin Jimenez claims his client's future is uncertain at this stage.
"At the moment, his future is undecided," Jimenez told O Jogo. "We need to speak with Benfica and to discuss the options.
"There is interest out there this summer from clubs in England and Italy and I believe they have had contact with Benfica.
"After a big season it is normal that significant clubs will be interested. Now the decision is in the hands of Benfica.
"Salvio is content at the club but he is open to the possibility of a move."