The Premier League club have sent scouts to Portugal to check on the Brazilian, and saw him feature in his club's 2-0 defeat to Porto on April 20.
Luisao is refusing to discuss any potential deals at the moment, but admits that his time in Portugal may be coming to an end.
"I have demonstrated my ability over the last few years with Benfica, but I have no desire to speak about my future until the end of the season.
"The club are aware of my position, and if they receive a good offer for me then I have a good chance of leaving Portugal."
A director of Benfica has also confirmed that the club are prepared to do business, should their valuation of the player be met.
"We will study the futures of a number of players in June, and if an offer arrives which is deemed to be suitable then we will consider it."