The winger is into the final year of his contract as is Alfredo Morelos.
Joe Aribo, who was in the same situation, has recently been sold to Southampton in a deal which could be worth up to £10million.
Ferguson is confident Morelos will stay put but is more wary of Kent’s future.
"The Leeds thing keeps popping up every now and then and I'm sure he wants to go back down and try himself in the Premier League," he told Go Radio.
"Rangers would love to keep both, but money talks and every player has a price on their head. If that price is met, Rangers will do business.
"During pre-season Gio will be sitting down and getting a vibe, whether they want to stay or whether they want to go. Over the next few weeks, you'll start to get news coming out about whether these two players will commit."