Can i salvage this build?

First time i got to the Epilogue and i cant kill nearly anything in a timely manner and cant survive maps over tier 2, so i was hoping to salvage this build since it was quite an time investment https://pastebin.com/FPS2pzSE

Well sorry to say this, but basically everything is wrong with this build so "salvaging" it would be trying to remake it into a completely different character, and I don't even know if you have resources / currency to do it and is it even worth it over levelling another character.

In my opinion best thing you could do is find a guide for a build you'd like and isn't very expensive, and has some tips for levelling / building up before end gear, then start another character and follow the guide.

The character of yours doesn't follow any basics of POE's rules of building character, namely:
1. Your main skill has no support gems that actually add good damage to the skill. You will literally do no damage. You have caustic arrow and siege ballista and neither of them are supported by anything worthwhile.
2. You have no auras. Not counting poacher's mark on blasphemy because it's a very useless skill all things compared.
3. You have extremely low amount of life both on your gear and your passive tree.
4. Your lightning resistance isn't capped.
5. You have 1 lab done (2 ascendancy points) at level 70 and it's probably one of the weaker nodes your ascendancy has.
6. Your skill tree has bad pathing with wasting a lot of points.
7. You invested a lot into leech while if you can't do damage, you can't leech. Caustic arrow is also an awful skill for a leech build. Tbh your whole talent tree and picking Alira means you probably shouldn't play caustic arrow.
8. You're picking jewel slots without having good jewels. This is a waste.

The whole character seems like an amalgamation of half of ice shot build and half caustic arrow, and it's really hard to guess what's that build meant to be.

You're also wearing items that are absolutely awful like deerstalker boots and that empyrean spiral ring, you can probably buy items 2-3 times better for 1 alch (if not SSF / console). That's another reason why your life and resistances are low.

Anyway if you want to check out, this is a good guide for ice shot + barrage deadeye:
https://www.pathofexile.com/forum/view-thread/2660684
And this is a good guide for caustic arrow build (can be done as pretty much any ranger ascendancy, but it's from a raider POV mostly):
https://www.pathofexile.com/forum/view-thread/2077932/page/1

Anyway if you really want to "salvage" a build, these are the steps:
1. Find a skill you want to play.
2. Find what are good support gems for the skill (checking poe.ninja, written guides etc.), get a 4-5 link and slot them there.
3. Find what auras are used for builds that use that skill.
4. Get enough gear to be resist capped and have at least 4-5k life, that includes having at least 150% life from passive tree.
5. Find what kind of damage stats you need on your gear and passives to support the skill you're using. For example caustic arrow does not work well with a build that invests in accuracy, crit and leech. But lightning arrow or ice shot would fit.