Did Jayce and Viktor survive?
I don't believe this is fully answerable, but I'm leaning towards yes; they survived in some form.
for one thing, I feel like if Viktor knew/believed they were definitely going to die, he would have fought harder to get Jayce to leave.
What I see in their faces is not resignation towards death, but undertainty and awe mixed with fear.
generally, the visuals of the scene really don't imply to me that the two of them were destroyed. in fact, I have a theory for specifically what did happen
first, it seems like the gem is charging up to do something.
But what? why was it necessary for Viktor to do anything at that point besides free the souls he was controlling?
They are right in front of Ekko's anomaly at this point.
(The gold light is the souls Viktor was manipulating, now free.)
Then, something new that appears.
Might be harder to tell in the still image, but those purple pillars are new, and don't seem to be part of the existing structure.
It's a bit uncertain, but I believe this not a part of Ekko's, but instead is a new anomaly. A space-time anomaly the two of them are creating, with the help of the souls.
You can also see that they are starting to become more distorted--earlier, their glowy forms were smooth--in the same way Jayce, Heimer, and Ekko had right before they were transported.
An anomaly is above them in this moment
I believe that is Ekko's, and one of two things have happened to the purple one. Either the angle just isn't showing it... or it's actually merged with Jayce and Viktor.
The transition from their golden forms to these purple-and-magenta ones is a single cut, and we don't see a transition. But it's at the same time that the purple anomaly disappears.
Then, the key final moments. I made a slowed gif (warning for slight body horror):
(Or go to this video if you a higher quality clip)
The stone becomes bright, and transparent, and jitters around, but it doesn't seem to be disintegrating or fading away. Not just Jayce and Viktor are pulled in; notice how the aurora-like stuff in the background, which is the anomaly from Ekko's explosion, is also grabbed?
That relates to my theory.
I'm not the first to see this tweet:
The acceleration rune is the rune used to power the teleportation of the hexgates.
I'm also not the first to note that the explosion Ekko started out of desperation? Basically fizzled out. Asides from a minor energy burst, there was very little damage.
My theory is that Jayce and Viktor removed the anomaly. Not just shielded the damage, or canceled it out, but actually teleported it along with themselves somewhere (or when) else.
Bonus: the rune is also used to free the souls of everyone controlled by Viktor. (That blue shape is the rune.)
Then they are flying in and around the anomaly(ies). I wonder if they too, are out there alive somehow...
