Newcastle saw previous attempts to sign the midfielder fall through on a number of occasions but, as revealed by Goal, the Magpies made a breakthrough in their pursuit of the 24-year-old with a £9.5 million bid earlier in July.
Montpellier chief executive Laurent Nicollin has since confirmed an agreement with the St James' Park club, and Courbis says the deal is "90 per cent" complete.
"This is not done yet," Courbis told RMC Sport. "Talks continue about the traditional bonuses. I'm not really worried about the outcome.
"Laurent and Louis [Nicollin, owner of Montpellier] were right to say no to a first offer which was upsetting. We're getting close. It's done at 90% but not at 100% yet".
Cabella was part of Didier Deschamps' France World Cup squad which was eliminated by finalists Germany at the quarter-final stage.
Despite being picked ahead of the likes of Manchester City's Samir Nasri, the playmaker failed to make an appearance off the bench in Brazil.