The Magpies will pay an initial £6.97m to sign the forward, with a further £1.7m due in bonuses if the move is successful.
Gomis must agree personal terms before a deal can be concluded for Newcastle's first summer signing, with Aulas expecting the move to be finalised in the next 48 hours.
He told Le Journal du Dimanche: "We agreed on Newcastle's offer for an €8m transfer plus two million in bonuses. The club has come to accept the player's salary claims.
"The deal is now subject to an agreement over the agents fees. I understand there's a problem over the amount and the payment of the fees.
"Hopefully, it would be settled within the next 24 or 48 hours."
The 27-year-old scored 18 goals in all competitions for Lyon last season, while also earning his 10th international cap for France.