Gab'borah Hise was once a very respected head cook at a Mos Eisley cantina when his culinary skills caught the attention of Jabba the Hutt.
Being the "generous" gangster he is, Jabba made Gab'borah an offer he could not refuse. So with no other choice Gab'borah moved into Jabba's Palace and joined the other dozen's of dessert chefs. Gab'borah's specialty at the Palace was making a sweet candy called a Ziziibbon truffle that to his knowledge was the only of it's kind throughout all of the galaxy. Later on Gab would use this as leverage to bribe Jabba's right-hand man, Bib Fortuna, to escape being thrown into the Sarlacc pit after making the mistake of not fully-cooking a collypod in one of his dishes and it in turn burning the major-domo.
As far as his importance in relation to Boba, Gab'borah is one of only a handful of people to call themselves friends of Fett. The two first met one another shortly after Boba was brought onto Jabba's sailbarge when he passed the ganglord's test for hiring him as a bounty hunter. Befriending the old man would later turn out being a blessing in disguise when the ancient bounty hunter Durge came hunting for the young Fett. Luckily for Boba, Gab'borah had an old jetpack saved to the side in case of a future emergency came when he might have to flee Jabba's wrath. However, Boba's need for it was immediate so Gab' gave it to the young man to use in fleeing from Durge.
Source: Boba Fett: Hunted