If you want to get lots of subs on YouTube you should try and tell your friends to subscribe and watch your videos. Also tell them to upload it on social media sites where a lot of people can see it and they will watch it and they might share it. Another thing is target you audience find a way of getting people who like watching you kind of videos. The way you will do that is find website for gaming and in the forums you can post stuff like, I'm doing a walkthrough for this game, what do you think of it so far, those kind of things. Try to interact with your audience, like make a twitter account where all your subscribers can connect with you and give you ideas for next videos etc this will boost your chance of more people finding out about you.Another thing is at the end of a video have a subscribe button where new viewers can just click and subscribe, also have like a previous video section where you show your previous videos, so people can just click the link and go to the last video you uploaded.
Doing this kind of stuff will boost your subscribers, if you want help tell me and I will give you my email.