What is the English equivalent of the Persian word "Saghi" (ساقی)?
Solution 1:
If you want to know what word to use when translating poems, I think it would be best to look at what human translators have used in the past, rather than turning to Google Translate. Here is a poem translation "Saghi-Nameh" where the word "bearer" is used (the term "wine bearer" might be used to clarify the meaning).
Two other terms, "wine server" and "cup bearer," are listed in this Wikipedia article: Persian Wine.
To me, "wine bearer" and "cup bearer" sound old-fashioned, but the custom itself would probably seem old-fashioned in English-speaking countries. The term "wine server" sounds less old-fashioned.
Solution 2:
As saghi is a typical Persian thing I don't think you will find an English word that would fit. I would take the Persian word and give a short explanation as "the cupbearer" or "he or she who pours the wine for the guests".