Some gorgonian are filter feeders and some get the nutrients they need from your lighting. If they are light feeders, make sure you have the right lighting for them. If they are filter feeders then you need to feed them phyto plankton. So that may be the problem.
On the other hand it might be a water quality issue. What are your levels, including your calcium, ALK/KH, ph, This could be the source of your problem.
Then there are some that just don't do well in tanks, they will make it for a few months, then they go down hill.
Your question is hard to answer with knowing which gorgonia you have, there are some many different types. Several red, and several yellow so we need to know which ones, We need to know your tank levels, everything about your tank. level, filtration, How old your tank is, ect.
It will be easier to help then.