I decided to test this Elven vs. Elven Gilded armor thing, since my High Elf prefers Elven things and would still like to reach the armor cap eventually. She's an Illusion-using sniper, so she doesn't get hit much anyway, but I'd prefer it if one hit didn't mean insta-death, at any rate.
Without any mucking about in the console, at level 35 I've already given her Agile Defender 1/5 and Custom Fit 1/1. Her Light Armor skill is 50.
Her usual armor set includes an Elven Gilded Armor with a Fortify Light Armor enchant, so the first thing I did was to console in a plain Elven Gilded Armor for testing purposes.
I haven't powerleveled Smithing or Alchemy on this character either--she can improve Elven Armor to Exquisite. She does not have the perk for Elven Smithing nor a full set of Fortify Smithing or Fortify Alchemy gear, but for the purposes of this test that shouldn't make a difference, as I am only testing whether the Elven Gilded Armor still gives a set bonus or not.
Apparel: Armor Rating
Elven Boots (Exquisite, Fortify Sneak): 24
Elven Bracers (Exquisite, Fortify Archery): 24
Elven Helmet (Exquisite, Fortify Archery): 33
Elven Gilded Armor (unimproved, unenchanted): 63
Total Armor Rating: 194
If I switch out the Elven Gilded Armor for Elven Armor (unimproved, unenchanted): 53, the total armor rating is 183, as expected.
Now for the console tricks. I set my Light Armor skill to 70 and give myself the Matching Set perk.
After doing this, my Armor Rating wearing the Elven Armor is 221, and my Armor Rating wearing Elven Gilded Armor is 203. There you have it; I guess it doesn't count.

BUT (and this is a big but) if you're not using the Matching Set perk, the Elven Gilded Armor is still better, and according to the beginning of this thread, the Matching Set perk isn't necessary to reach the armor cap. So do with this as you will.