You just have to look at what is trending on youtube and include the key words in to your titles e.g. "Jake Paul reacts to Grand Theft Auto 6 Beta. You wont believe what happens next...... (QNA)" or "White Supremacist Neo Nazi stops the Grand Theft AutoTrain. GTA6 free giveaway".
Basically copy Sernando.
Seriously though, use tags that describe the video. Obviously GTA 5, GTA V, GTA Online. If Im looking for a video about a newly released car or DLC I will search those terms i.e. "GTA ardent" or "GTA gun running". The tags you use will depend on your content, just make them relevant and unique enough for them be searchable for someone who is looking for GTA content.