TBH after a year and a half having 1600 subs isnt bad at all you are actually doing better than I am and I have been at it longer. The only thing that I would say you could benefit from would be:
Channel Trailer- I think you could benefit from a channel trailer to give people a good idea of what your channel is about rather than having your most recent video in the trailer spot.
Video THMBnails (You Know this)- Alright, you gotta get some thumbnails bro..... look into some sites that have some pre-made templates for the games that you play here is a template for GTA 5 that you can edit in photoshop>
http://www.mediafire.com/download/ds1ol4oqjp1m4in/GTA+Thumbnail+Template.psd < thumbnails are very important to say the least, they provide the first impression for your video and draw people in.
Playlists- Maybe have some type of series that you could create another playlist for, overall you only have your recent uploads, activity and popular uploads. You need more variety in your content/playlists.
Annotations/Cards- I watched a few videos and didn't find and annotations or cards, i recommend using them to redirect traffic to your premiere or new content.
Outro/Call to Action- You need to create an outro that using the annotations to redirect traffic to more of your content as well as a call to action that tells people to like comment subscribe. Typically the CTA works best if you say it in your outro I know you have a struggle speaking though so you can start with atleast having the outro portion.
I also have a post requesting your feedback on my channel check it out and return the review please >
http://yttalk.com/threads/review-thefreshbiz-help-me-out.187570/
