I can attest to that. I started just over half a year ago and was mostly getting cents for my posts, with the odd one being curated. I made it a goal to reach 500 SP and slowly my earnings have increased and my following too. There are others who have been around as long, sometimes longer who have yet to reach 500 SP because they take out the other 50% and their posts seem to reflect that in their earnings.
Once I reached 500 I did remove some steem to pay down out mortgage a bit, but mostly to see if it could really be spent in the real world. Now I plan to build that steem power up a bit more.