Gilmoy: 30.Nxh7! is a special case of <demolition of pawn structure>. Accepting with 30..Kxh7 creates a "bowling alley" pattern, with Black's K trapped on h and exposed to a two-Rook mate theme. This trumps White's material deficit, since none of Black's extra pieces can block on h.
[A] 31.Qh3+ Qh6 (Qh4? 32.f6+) 32.f6+ N(either)d3 too hasty -- but it reveals Black's defensive resources. White wants to transfer his QR to h, and/or destroy Black's d3 strong-point to make his Bb1 unblockable. Hence:
[B] 31.Rxc4! deflects Black's double on d3. White threatens 32.Rh4+, Black's Q is overworked defending h4 and g7, and Black has no useful way to block the R from h4 or add a defender to g7. Hence, Black must accept: 31..Nxc4 32.Qh3+ Qh6 33.f6+ and now:
[B1] 33..Ne4 34.Qd7+ wins: (B,R)e7 35.Bxe4+ Kh8 and either 36.Qxd8+ mate in 2, or 36.Qxe8+ Bf8 (Qf8? 37.Qh5+) 37.Qe6 and Black can't defend g8.
[B2] 33..Re4 34.Bxe4+ Nxe4 35.Qd7+ and mate at g8.