The team sent both players down to the minor-league affiliate this past Thursday as the Leafs began their bye week.
Dermott made his NHL debut and recorded his first career assist in a Jan. 6 game against the Vancouver Canucks earlier this month and also suited up for a Jan. 8 contest against the Columbus Blue Jackets before being a healthy scratch Jan. 10 vs. the Ottawa Senators.
The 21-year-old was a second-round pick of the Maple Leafs (34th overall) back in 2015 and has 18 points in 28 appearances with the Marlies this season.
Gauthier, 22, saw action in five games with the Maple Leafs this month, going minus-4 and failing to register a point while averaging 8:27 of ice time.
The team is preparing to host the St. Louis Blues Tuesday.