Tiers are based on 2 factors; depending on where your profile lands (Pornhub or PornhubGay)
Rank bracket - The first qualifier is based on what rank bracket you were in from the previous quarter and how many days you were there. Being in your rank bracket for more than 46 days during the quarter will help you move up. There are multiple factors of how users engage with your content that will also determine your rank.
Uploads - Second, it is dependent on how often you upload to Pornhub. Consistently uploading new, high-quality videos that are 7 minutes or longer will help you reach higher Tiers and a higher payout.