The Reds reportedly considered signing the Sao Paulo star during the last transfer window, but backed off when the work permit issue arose.
However the player's agent Paolino Oscar told The Echo: "They had revealed interest in the past one or two months, when the window was open.
"Now, I find that it was more difficult because everything is closed in Europe.
"It is in Sao Paulo's hands and it is they who decide. If Aislan is told to leave, very well. If not, that is good also.
"I have respect for Sao Paulo and I do not do blackmail, therefore it is the club who must make the primary move."
Sao Paulo are hoping to receive a substantial fee for Aislan, who has a release clause of £10.5m in his contract.