how much Elo rating does learning openings translate to?

I dont see how that is answerable since there are many ways to study openings. Maybe I can take a shot at a different question: How to study openings to maximize your performance improvement? At the start [which is where I think you are] basic tactics are most important: puns, skewers, xray attacks,... For openings, I'd suggest studying games where strong GMs beat lesser ones like rented mules, like "Morphy vs Amateur". When you see a game where you feel inspired by how the pawn structure leads to the play, study that opening just enough to see how you get to that structure. When you play it just head for that structure as best as you can and play good moves as best you can. Openings are just about getting a position you feel good about playing and have some idea how to develop your position from there. So study GM games and look for play that you understand and find inspiring. "Simple Chess" , "Best lessons of a chess coach" are good places to start. And, win or lose, have fun!

indeed. As usual, its obvious that if you know the opening played better than your opponent, you are at an advantage. Especially as white. Yeah, even at your level! Common sense. Even having more experience in a certain line, without having full grasp of certain key points, is an advantage. Elo is another topic altogether at your level soo...meh...don't worry about it. Hell, I've been playing for 30+ years and I never thought about elo points...ever! Just play, worry about stuff like that later. Because for me, playin's the thing. ✌🏽

Development is all you need to know about openings at 1000 elo. Get all your pieces and castle. Pawns in the center. Simply developing will take you to 1400 elo. It does not make a lot of sense to remember lines an theory if your opponent is going to deviate on move 5 with a mistake or blunder.
This is why learning "set up" openings can be helpful. The London system is a setup opening. The Stonewall is a setup opening. Theses are openings where you are almost always going to to play the same 8 moves at the begging of the game. You will reach the same pawn structure every game. This is particularly helpful when you are trying improve because you can focus your attention on other more important things like TACTICS.