The Maple Leafs find themselves in a similar situation as last year which saw the club lose James Van Riemsdyk to UFA at seasons end.
Although the Leafs would prefer to keep Jake Gardiner (I know some fans might disagree) it is not logical financially, It would require a trade of a roster player for salary relief. One situation that could open up space is trading Nikita Zaitsev, he carries a 4.5M cap hit for the next 6 years. This signing was the last from former Maple Leafs GM Lou Lamoriello.
Jake Gardiner currently makes 4.05M a year and is rewarding of a raise (again, I know certain fans disagree) and expected free agency money for a 40+ point defenseman is in the 6-7M per season range however the Maple Leafs would likely put pen to paper in the 5.5M range which is still steep for a club fighting to stay under the cap. In a best case scenario Gardiner would take a discount to remain with the Leafs in the 4.5 to 5M a year range for 4 or 5 years.
If you were in a city that brought you to tears for booing you on home ice, constantly criticized you and held you under a microscope would you resign for less than your worth?