Help me to interpret this sentence -
And each time we do this, we learn to repeat the process and it becomes a habit. So later, feeling stressed out triggers that urge to smoke a cigarette or to eat something sweet.
Now, with these same brain processes,
**we've gone from learning to survive to literally killing ourselves with these habits. **
Obesity and smoking are among the leading preventable causes of morbidity and mortality in the world.

Question.
1. [we've gone] means "we've been staying"? What does that mean exactly?
2. [survive to literally killing ourselves] means "prevent to suiside"?
3. I don't understand well why [to killing ourselves] was used. "killing" is a noun in the sentence?

Question

Help me to interpret this sentence -
And each time we do this, we learn to repeat the process and it becomes a habit. So later, feeling stressed out triggers that urge to smoke a cigarette or to eat something sweet.
Now, with these same brain processes, 
**we've gone from learning to survive to literally killing ourselves with these habits. **
Obesity and smoking are among the leading preventable causes of morbidity and mortality in the world.

Question. 
1. [we've gone] means "we've been staying"? What does that mean exactly?
2. [survive to literally killing ourselves] means "prevent to suiside"?
3. I don't understand well why [to killing ourselves] was used.  "killing" is a noun in the sentence?

Answer

1. [we've gone] means "we've been staying"? What does that mean exactly?
We've gone -> we have gone. The verb is "go". "go" denotes movement, right? Change? It means "we have gone from point/state/situation to another".

2. [survive to literally killing ourselves] means "prevent to suiside"?
You're grouping the words wrong. It's not "survive to literally killing ourselves". It's "from learning to survive" and "to literally killing ourselves".
"learning to survive" is point A
"literally killing ourselves" is point B
We have gone from point A (from learning to survive) to point B (literally killing ourselves).
(A점에서 B점까지) except point A and B are not places, they're situations or states.

3. I don't understand well why [to killing ourselves] was used. "killing" is a noun in the sentence?
Yes, killing is a noun, specifically a gerund. Just like "learning" in "learning to survive".
I like DRAWING. Drawing is a noun, a gerund.
= 는것

Answer

1) "We're gone from " we moved from a state to another .

2) We are gone from " learning to survive" to " literally killing ourselves with these habits 
We moved from a state of survival ( in this case trying to cope with stress) to extensively indulging in these bad habits to the extent of jeopardizing our health and life !

3) And yes 'killing ' is a noun here , a gerund in fact . 
From surviving to killing ! 
It is direct speech no figurative metaphor here by the way !

Answer

We've gone from (something) to (something) > this phrase means being in one situation earlier and then to be in another situation later > My English has gone from bad to worst 
He has gone from a skinny boy in childhood to the what he is now.

survive to literally killing ourselves > literally means exactly what the words mean, and in this case the words  are "killing" themselves, meaning they are actually killing themselves ( no other meaning other than what the words mean) . > I hated him so much , I literally hoped he died > you actually the meant that he should die . / Don't take what I said literally> don't take my words to mean exactly what they meant .

to killing ourselves > verb +*ing*= gerund can act like a noun . I have gone from liking her to hating her

Answer

"We've gone" in this case means "We've progressed." Even though the author is saying that we are killing ourselves, this is not intentional suicide. It is done unintentionally.

Answer

I agree with Cherry - it's not a metaphor!