You have a really low CTR rate,
You have to test different ad placements,different positions , try using ad networks etc.
I think CTR of 0.31% is actually pretty high (considering specifics of the website).
Freebitco.in doesn't allow you to modify size and placement of your banners, you can only experiment with changing colours/appearance.
But you're right, the traffic is not very valuable. If someone is scrounging on a faucet for a few pennies, they probably don't have much to spend on the site you're advertising.
Yup, comparing to adsense it's supercheap, but with adsense you can pay for clicks not views. With freebitco.in it's not guaranteed that you'd get any clicks at all.
But adsense is out of the question, they won't allow bitcoin gambling ads (or any other gambling ads).
I expected it to be higher.
Not even a day, more like few hours.
What did you expect to be higher? CTR or CPC?