Obviously buffs aren't top tier...running Kupofried, Qultada, Joachim, Koru, and Yoran. Fudo is hitting anywhere from 7k to 11k on average I would say (just eye-ing it).
Hard to give off some numbers, because it depends on a number of things. Gear, trusts, Gifts. How many JP do you have?
A 3-5 step should easily decimate any bat in Dho Gates, so your set is a little low. I honestly would drop Kupofried, since that CP Bonus you gain from the trust is less vital if you're not killing
as fast as you would with another trust, like a support. Sadly, there aren't many options you can go to. The only obvious ones I would suggest is
Replace Kupofried with Shantotto II (huge dps increase)
Replace Apururu with Sylvie
Koru/KoH is roughly the same, but I'd go with the latter
Shantotto II is very very useful. She doesn't increase
your dps, but it's the same thing essentially. She will (occasionally) interrupt your SC (as will Qultada), but she wil burst 1-2 spells off of each SC, for roughly 5k-8k dmg each. In a standard 3-step, that's about 32k extra damage just from nukes, if you space out the WSs properly.
You can also drop Qultada after he rolls 2 good Phantom Rolls, and replace him with something like Ulmia. She'll toss out DD songs and ballads, which will help out a little. but she's not a great trust to be honest, so you can afford to do better here (I use Cherukiki instead). Then summon Qultada back when rolls wear off in a rotation.
For CP farming
On Samurai, I hardly feel like a Healer UC trust is necessary, since KoH/Joachim/Sylvie can easily keep you alive, even if you draw a couple aggro. Cherukiki will suffice, Sylvie will use
Entrusted Indi-Frailty for about 18% defense down (which stacked with Dia III), so that's decent. She'll also use Indi-Fury for a huge attack bonus, as well as Heal/NA/Erase you very quickly. Those few trust changes are IMO a very ideal swap for strictly soloing CP as fast as possible on SAM.
Now, onto gear improvements.
The obvious upgrades would be to swap Brutal for Moonshade in nearly every SAM WS set. You should work on getting that, if you haven't (the quests are long I know, but well worth the return). You can also look into swapping out Brutal Earring for Lugra+1 during Nighttime, but yeah. I'd also challenge you to try using Flamma Ring + Flamma Head/Feet+2 if your augments aren't the best. You may see higher STR using that setup.
Goes without saying: Work on those Valorous Augments until your fingers bleed xD. The body augments seem fine,
but anything less than 15STR+3WSD (OR) 10STR+4WSD (depending on the stone you use) can be improved significantly. I would say keep rolling those (I used Taupe + Pellucid cuz they are cheaper but meh)
Obviously quick upgrades: Wakido Legs+3, Utu Grip, Ifrit Ring +1/Regal. You're doing Omen apparently, so a couple of those are not out of reach for you.