My gardenia bushes are dry, brown, and brittle as of 5 weeks ago. Are they dead or just dormant?

Yeah they are on their way out. If they are in the wrong position to get at least 8 hours light then i'd suggest moving them. Water and mulch they should come back. I have a hedge of gardenia's and one did look like that but have put it in a sunnier position and it is coming back fine. I good test to see if it still has life in it, is to use your thumb nail and scratch the trunk a bit. If you see green under the bark our outter layer than its still has a chance. You'll know if its dead when you scratch it.

Kung Fu school