With hardfork 19 the rewards are linear, so yes if you get $x out of one upvote with y SP, then you get $10x for a 10y SP upvote. The problem is, first of all, the reward is currently decreasing because the reward pool is still adjusting to the increase in rewards. Second, how do you know it is 0.02, and not 0.017, or 0.024?
But ok, assuming your upvote is worth exactly $0.0200 and that you have exactly 100 SP, then you would need 50*100=5000 SP to get to $1. For that, we ALSO have to assume that the SBD price won't change before you get that much SP, which obviously it will.
Ok some more info. Based on this article https://steemit.com/investment/@cryptoctopus/cashflow-or-capital-appreciation-what-is-the-true-value-of-steempower by cryptoctopus, you get
as of right now. $1000 worth of SP is 522SP right now. So the answer to your question is, right now 522*4=2088SP are needed for a $1 upvote. However, if we follow this rule, then the 125 SP that you have should give you $0.059, not $0.02... So my guess is that the correct answer is between 2100SP and 5000 SP. The best way to know would be to find someone whose upvote is worth more than 0.50 so we can be more precise.
I found the definite answer guys. Here's how I did it: I went on https://www.steemnow.com/ and put in jesta as username. There you can see he has almost 100% voting power, and that his 100% upvote is worth $14.27. You also see his SP. if you divide his total SP by 14.27 you get around 2800SP. I tried with other steemers with a lot of SP and its around 2800-3000SP when their voting power is around 100%, so here it is folks.
The answer is : around 2800SP when you're at 100% voting power, as of today (this value will increase because payouts are still decreasing)
thanks for the good answers ☺