Is this line of vienna attack a draw? Most chess players will recognize this position from the so called immortal draw:

[FEN ""]
1. e4 e5 2. Nc3 Bc5 3. Na4 Bxf2 4. Kxf2 Qh4 5. Ke3 Qf4 6. Kd3 d5 7. Kc3 Qxe4 8. Kb3 Na6 9. a3 Qxa4 10. Kxa4 Nc5 11. Kb4 a5 12. Kxc5 Ne7 13. Bb5 Kd8 14. Bc6 b6 15. Kb5 Nxc6 16. Kxc6 Bb7 17. Kb5 Ba6   


I am trying to understand if after Bxf7+ it is a force draw (with best play), I checked this opening site and after Bxf2 there is almost 88% of draw in this position.
With best play, the position is unclear. If White plays 7. Kc3, then after 7...d4+!, Black gets a slight advantage. However, White can play 7. Qe1! and then the position is unclear. 

    [FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

    1. e4 e5 2. Nc3 Bc5 3. Na4 Bxf2+ 4. Kxf2 Qh4+ 5. Ke3 Qf4+ 6. Kd3 d5 
    7. Kc3 (7. Qe1 $1 Nf6 8. c3 Bd7 9. Kc2 (9. Nc5 Bb5+ 10. Kc2 Qxf1) 
    9... Bxa4+ 10. b3 Qxe4+ 11. Qxe4 Nxe4 12. bxa4 Nf2 13. Ba3 Nxh1 14. Nh3 f6 
    15. Bd3 Ng3 16. hxg3 Nc6)
    7... d4+ $1 8. Kb3 Qf6 9. Nf3 (9. a3 Qc6 10. Ka2 Qxa4) 9... Bd7 10. a3 Na6 
    11. Ka2 Bxa4 12. Bc4 Bd7 13. Rf1 Qe7 14. d3 f6