This is the church book from 1749 in Flesberg parish and I'm looking for Gullich Olsen born 1749. I believe he's the third box down on the upper left on this page? Having a bit of trouble with this person's handwriting. :) I suspect his father's name is Ole Gullichsen although that's just a guess at the moment. Thankfully there are only two pages for 1749!
According to Flesberg bygdebook (vol V), Ola Gullekson and Kari Kittelsdotter at Fønnset had three sons named Gullek. The first born and died in 1749, the second born in 1750 and died in 1755, and the third born in 1758 and died in 1845. He married Maret Helleksdotter in 1789.
Did you look for the birth of the Gullich Olsen who married Maret Helleksdotter? Or this one in the 1801 census, who married Gjertrud Pedersdatter? According to Flesberg Bygdebook, this latter one was the son of Ola Hellekson and Jårån Gulleksd. His baptism should be the one in the second box of the second column here.