Gestede scored his second goal of the season with a close-range finish following good work down the right by Craig Noone.
Kerslake said: "Rudy is an outstanding professional. He came in, took his chance and will play a major part in what we are trying to achieve this year. He is a huge option for us.
"We didn't have the strength of depth last year. Now we've got players like Heidar Helguson and Don Cowie coming off the bench.
"We couldn't do that a year ago. Certainly our squad is one of our big strengths now.
"We knew we had a really tough month coming into the festive period. We applied ourselves the way the manager expects us to do. We've been delighted with the results."