Hello mermaid8801,
Welcome to Expat.com 
It really depends on various factors. Your ability to live comfortably on a salary of 857,000 ISK before tax in Iceland will depend on your lifestyle, whether you have children and the location where you plan to live.
The cost of living can vary significantly.
Hopefully, someone on the forum will be able to shed some light on this.
Cheers,
Cheryl
Expat.com team