Are you playing Hitman 2 from 2018 or Hitman 2: Silent Assassin? According to
reshade.me/compatibility
, the latter one uses Direct3D 8, in which case you would need the D3D8to9 wrapper and ReShade's d3d9.dll.
Another reason may be that you chose the wrong exe file, sometimes the actual executable is in another folder (such as a 64-bit version). Open Task Manager while the game is running to check (Ctrl+Shift+Esc).