There are two Bible references to people being cup bearers:
2 Pharaoh was angry with his two officers, the chief cup bearer and the chief baker.
11 Lord, I beg you, let your ear be attentive now to the prayer of your servant, and to the prayer of your servants, who delight to fear your name; and please prosper your servant today, and grant him mercy in the sight of this man.”
Now I was cup bearer to the king.
There are also references to King Solomon having cup bearers:
4 When the queen of Sheba had seen all the wisdom of Solomon, the house that he had built, 5 the food of his table, the sitting of his servants, the attendance of his officials, their clothing, his cup bearers, and his ascent by which he went up to the LORD’s house; there was no more spirit in her.
The Bible references don't give any indication of the importance and high rank of the position. A cup bearer served drinks at the royal table. Because of the constant fear of plots and intrigues, a cup bearer had to be thoroughly trustworthy to hold the position. He had to guard against poison in the king's cup and was sometimes required to swallow some of the wine before serving it. His confidential relations with the king often gave him a position of great influence.