How competitive are these jobs? If I am a fresh college graduate with a degree in CS and I have a portfolio that consists of one self-published and self-developed game with a little over 1k units sold, would that put me way ahead of the curve or no (let's assume for the sake of completeness that the game in question is quality enough to showcase and be proud of on an interview)?
Having a game to show is always good, ofcourse. But as far as I know, you WILL be tested on your coding and knowledge during an interview. If you made a small game in a month, then great, but if you spent 2-3 years on a game a normal developer could finish in 1-2 months, you might be in some trouble ^^
It all comes down to what YOU know and how good of a programmer you are. getting a degree is a good way to learn, but its not going to code for you, and your employer wont be stupid, he will know if you can do what he needs or not after the interview.
This is all the info I can share, probably someone out here that can give a better and more detailed one :)
I can't tell you if it will help you very much, because I believe it depends on company and people working there (and doing interviews). But I can tell you this:
I was in similar situation 2 years ago. I was also looking for a job in bigger AAA game company (few month before my graduation, because after graduation a lot of people is looking for a job). And I was on an interview (and passed and was working there for a while).
I created 2 small games (in team) and had some other demos - like cloth simulation computed on GPU, some graphics demo using shaders etc.
First part of interview was with HR person. Some normal question as you can expect on every other interview. I didn't answered all of them, but maybe half.
Second part was interview with my future superior. He was asking me typical programming questions, like what is Singleton, some data structures questions, some puzzles, ... And he also asked me like 3 question about my demos (but it looked like he sees a lot of demos like this every day).
And then third part: I sat in front of a computer and had two hours to complete a small game - there was about 20 parts of game and I should complete as many as I could. I didn't completed all of them, but they wanted to test me - how I work under (time) pressure, how I deal with some hard tasks, how optimized code can I write (because this is pretty important in game programming). And I believe that this was the most important part for them.