I am sure all my sherdog brothers have this information, at the same time I am not sure how accurate it is but I am assuming it should be in the ball park. Here is Demetrious Johnson's UFC salary history. From what I see and in my opinion, he gets paid well for basically being a zero draw. It also seems like and I don't know when he last negotiated his deal, but he is being compensated pretty well for last few fights.
UFC 126 – Feb 5/11 – W (Yamamoto) – $10,000 ($5,000 to show, $5,000 win bonus)
UFC 130 – May 28/11 – W (Torres) – $12,000 ($6,000 to show, $6,000 win bonus)
UFC Live: Cruz vs Johnson – Oct 1/11 – L (Cruz) – $20,000*
UFC on FX: Alves vs Kampmann – Mar 3/12 – D (McCall) – $90,000 ($20,000 to show, $20,000 win bonus – UFC paid it out despite the fight being a draw, $50,000 Fight of the Night bonus)*
UFC on FX: Johnson vs McCall – Jun 8/12 – W (McCall) – $40,000 ($20,000 to show, $20,000 win bonus)
UFC 152 – Sept 22/12 – W (Benavidez) – $46,000 ($23,000 to show, $23,000 win bonus)*
UFC on Fox: Johnson vs Dodson – Jan 26/13 – W (Dodson) – $102,000 ($26,000 to show, $26,000 win bonus, $50,000 Fight of the Night bonus)*
UFC on Fox: Johnson vs Moraga – Jul 27/13 – W (Moraga) – $108,000 ($29,000 to show, $29,000 win bonus, $50,000 Submission of the Night bonus)
UFC on Fox: Johnson vs Benavidez 2 – Dec 14/13 – W (Benavidez) – $225,000 ($125,000 to show, $50,000 win bonus, $50,000 Knockout of the Night bonus)
UFC 174 – Jun 14/14 – W (Bagautinov) – $179,000 ($127,000 to show, $52,000 win bonus)*
UFC 178: Sept 27/14 – W (Cariaso) – $183,000 ($129,000 to show, $54,000 win bonus)
UFC 186 – Apr 25/15 – W (Horiguchi) – $237,000 ($131,000 to show, $56,000 win bonus, $50,000 Performance of the Night bonus)
UFC 191 – Sept 5/15 – W (Dodson) – $231,000 ($133,000 to show, $58,000 win bonus, $40,000
Reebok sponsorship)
UFC 197 – Apr 23/16 – W (Cejudo) – $285,000 ($135,000 to show, $60,000 win bonus, $50,000 Performance of the Night bonus, $40,000
Reebok sponsorship)
TUF: Tournament of Champions Finale – Dec 3/16 – W (Elliott) – $390,000 ($350,000 to show, $40,000 Reebok sponsorship)
UFC Fight Night: Johnson vs Reis – Apr 16/17 – W (Reis) – $450,000 ($360,000 to show, $50,000 Performance of the Night bonus, $40,000 Reebok sponsorship)*
UFC 216 – Oct 7/17 – W (Borg) – $460,000 ($370,000 to show, $40,000 Reebok sponsorship, $50,000 Performance of the Night bonus)
I am not sure how many fights are in his current deal, but his next fight should be for $380,000.00. Which is damn good in my opinion for a flyweight.