Gorgonians are notoriously difficult to keep alive for extended periods of time in captivity. I don't think we have mastered their nutritional requirements yet. I tried twice with blue gorg. using rotifers, phyto, bbs & other particulate matter but to no avail.
BTW what type is it? If its a photosynthetic one, then those usually do better but I believe that non-photo. species require a large, well-stocked in-line refugium to do well. Once they start to decline, they often continue to melt away. Good luck with yours.
JME
Anthony