Gee willikers
Is this the same as "Gee whiz"?
Yes. "Gee whillikens" dates back to 1857. I Hear America Talking: An Illustrated History of American Words and Phrases by Stuart Berg Flexner (Von Nostrand Reinhold Co., New York, 1976). This substitution of a G-word for God follows ".the old Hebraic and Middle English tradition of avoiding the sacred words, such as God, by substituting words with the same initial letter." A Minced oath.
For more information, search the archives under "gee."