I think it's a forced win for black.
Black can start with
1...Qxc4 after which the next five white moves are forced to avoid a fast loss.
[FEN "6k1/5p2/1Pp3pb/2q4p/1rNpPP2/3Q2PP/8/5RK1 b - - 0 1"]
1...Qxc4 2.Qxc4 Rxc4 3.Rb1! Bf8! 4.b7! (4.e5!? d3 5.b7 d2 6.b8=Q Rc1+ 7.Kf2 d1=Q) Bd6! 5.b8=Q+ Bxb8 6. Rxb8+ Kg7
Black is a pawn up and has connected passed pawns and should try to exchange pawns to simplify to a won end-game. The game might continue for example as follows:
[FEN "1R4k1/5p2/2p3p1/7p/2rpPP2/6PP/8/6K1 b - - 0 6"]
6... Kg7 7.e5 c5 8.Rd8 Rc3 9.Kf2 h4! 10.gxh4 Rxh3 11.Rc8 Rc3
The computer still doesn't find a line that leads to an obvious win but it looks like a hopeless situation for white and the computer playing against itself gives a win for black. Here's an example way to continue the game:
[FEN "2R5/5pk1/6p1/2p1P3/3p1P1P/7r/5K2/8 b - - 0 11"]
1... Rc3 2. Rc7 Kf8 3. Ke2 c4 4. Kd2 Rf3 5. Rxc4 Rxf4 6. Rc8+ Kg7 7. Rc7 Re4 8. Re7 Rxh4 9. e6 Kf6 10. Rxf7+ Kxe6 0-1
The final position is a table base win for Black.
If you think there any errors in this analysis (in particular, weak moves for white that changed the value of the position from drawn to lost) then please let me know.