For context, those numbers came from 2014. http://www.businessinsider.com/bitcoin-inequality-2014-1
I can't find any more recent study specific to the Gini coefficient, however these[1] charts show an improvement over this snapshot[2] from May 2015.
[1]: https://bitinfocharts.com/top-100-richest-bitcoin-addresses.... [2]: https://www.cryptocoinsnews.com/1-bitcoin-community-controls...