One can earn interest by providing loan to users and getting a limited percentage of bitcoin as interest for the provided value based on the agreed statements between provider and the beneficiary.
I think the OP just made this thread to promte his fucking scam/ponzi website cause he was last active one day after this post and says he used it loll.
How do you earn interest on BTC?
The same how you would earn interest on fiat currency.Without your ponzi,of course.
He seems to be promoting his ponzi website here as he has posted a positive review about the website without any proof. There are very few genuine websites that pay users 1% interest daily and they are genuine but 90% of ponzi websites are just scam ones. It's better to invest in forex websites as they are more trustworthy. With regards to fiat currency, bitcoins aren't exactly the same.