Earnings are very individual and depend upon several factors. First of all, it takes awhile to get Adsense rolling. It may take months-- or more-- to see significant earnings. If you are persistent and patient those time spans begin to shrink. If you keep active, keep learning and keep putting the time in to create a quantity of quality content your earnings will rise.
People earn widely varying amounts, but the only way to find out how much you can earn is to try it for yourself.