How does winning/not winning the premier league affect Rafa Benitez's contract negotiations with Liverpool?

The Spaniard's contract is expiring in 18 months time. Reports say Benitez is unhappy with his current terms as Phil Scolari is mentioned to be receiving double Rafa's salary. The same report stated that ex-Newcastle United manager Kevin Keegan has a higher package than the man who won Liverpool their 5th CL trophy.