What are my prospects in this?

I opened up a YouTube channel and uploaded like 10-15 videos. I got 1-2 subscribers. Haven't advertized anywhere, I hoped to get an audience based on their search. So, I decided to quit, and started to work on another project. That was all a few months ago.

However, an interesting thing happened...I haven't closed the channel, so I accidentally noticed that the number of subscribers to my channel had has risen to around 50 in this last few months during which I haven't actually done anything.

What do you think I should do? Is that a sign of potential huge "organic" growth? Do I keep uploading videos, and after a while expect the subscribers list to start increasing exponentially?

Do you perhaps have some ideas in regards to advertizing of my channel, to make it grow more rapidly?

You should keep uploading videos to figure out whether it is a sign of huge organic growth or not. I experienced this situation at least 10 times. Sometimes i got good results. I suggest you to use a ranking method after uploading at least 5 more videos.