Vettel recently invited Mercedes chief Toto Wolff to his 30th birthday party in Switzerland, with Red Bull chief Christian Horner saying: "I would think he's got Toto in his ear saying 'Extend for a year (at Ferrari)'.
"And then he's probably got Ferrari saying 'It's three years or nothing'," Horner added.
Indeed, France's Auto Hebdo now reports that Vettel has been offered a new three-year Ferrari contract, valued at a total of EUR 120 million.
The report said Vettel would insist that, if he does stay at Ferrari, his friend and current teammate Kimi Raikkonen is also retained.
Auto Hebdo said Ferrari president Sergio Marchionne has agreed to a EUR 5 million extension for the Finn, although Raikkonen is yet to accept or reject it.
"I think the situation in the drivers market depends on Sebastian Vettel," said Horner. "But what is clear is that there will be no change at Red Bull Racing."