Since gaming now lives at http://YouTube.com/gaming , the old Gaming app is going away on May 30th! If you were subscribed to channels in the Gaming app, they’ll automatically move to your YouTube subs feed on May 14th. More need-to-know info→ https://yt.be/help/yRe4
Since you've met the eligibility & program thresholds, you can expect to hear back in a month or so. Note: all applications are still manually reviewed, so it does take a bit of time! If it's taking longer that likely means your channel is being held for a second review.