Frenchman Gaultier, going in search of a first title in Hong Kong, saw off Tarek Momen while Elshorbagy proved too strong for Spanish opponent Borja Golan.
Momen was appearing in the last four of a PSA World Squash Series event for the first time and, despite a promising start, struggled to keep pace with the world number one.
Gaultier, by contrast, has 25 tour titles to his name and the gulf in class showed as he saw off the world number 12 11-7 11-2 11-3 in just 36 minutes to move into the final.
There he will meet another Egyptian in the form of world number three Elshorbagy.
The 23-year-old booked a first Hong Kong final berth courtesy of a victory over fourth seed Golan, requiring 48 minutes to progress 11-7 11-5 7-11 11-7.
Gaultier holds the historical advantage over Elshorbagy - winning nine of their 10 career meetings.
However, the Egyptian beat the Frenchman for the first time in their most recent meeting, clinching a thrilling 11-6 14-16 11-9 12-10 success in the El Gouna International semi-finals earlier this year.