The Brazilian centre-back was initially on the radar of Everton earlier this year with The Independent revealing the player even underwent a medical in March.
But Napoli soon overtook the Toffees in the race and are thought to be close to agreeing personal terms, with the Italians enjoying a good relationship with the French club, having already signed Gabriel’s teammates Victor Osimhen for £63.3m.
Signed from Brazilian side Avai in 2017 for just £1.5 million, Lopez has confirmed the Ligue 1 side are set to make a big profit on the 22-year-old.
“The way we work is very simple,” Lopez told BBC Sport.
“We explain to him [Gabriel] and his environment, his agent, what we’re looking for, and once we get those offers the choice is his.
“We are there now, so we told him: Eventually you have to make a decision but we’re not pressing you.
“We help him out a little bit so we tell him: We think this might be the right manager or club for you.”
Lille have already secured the signing of Gabriel’s replacement, Sven Botman, from Ajax for around £7m.