Magalhaes is due to fly into London in the next 48 hours – but under new travel restrictions will then face two weeks quarantine due to coronavirus precautions, before he can start training with his new team-mates.
The Gunners expect to announce the deal for Gabriel, 22, after terms were finalised on the deal over the weekend, and the centre back agreed a five year contract worth around £80,000 a week.
The Brazilian underwent a medical in France last week.
Gabriel becomes Arsenal’s second summer signing, after the capture of fellow Brazilian Willian on a free transfer from Chelsea last week.
“But the board will probably tell him he has to get rid of players in that position if he wants to sign a new centre-back.”
Arsenal appear to have utilised their good relationship with Lille in order to convince him that they’re the right club for him.
The Gunners bought Nicolas Pepe from Lille for £72m last summer, and the two clubs are said to be on good terms.
Arsenal return to action next weekend when they take on Liverpool in the Community Shield at Wembley.