I have a gaming YouTube channel with around 5,000 subscribers. My new YouTube channel is different (pop culture), and I want to get as many of those 5,000 gaming channel subscribers to subscribe to my new YouTube channel. How many are expected to subscribe to the new channel by just asking (i.e. annotation on videos and/or commenting in the description)? What's the best way to get as many of them to subscribe to the new channel as possible?