Can White win from this diagram?
Yes, but his King must move backwards to attain the win. The process is known as Bridge Building and was discovered by Lucena in 1497.
1.Re1+ (To chase the enemy king so White’s own king can eventually move out of g8.) 1…Kd7 2.Re4! (This is probably how the term “Bridge-Building” came about. The king and rook need to link up with each other.) 2…Kd6 3.Kf7 Rf2+ 4.Kg6 Rg2+ 5.Kf6 Rf2+ 6.Kg5 Rg2+ 7.Rg4 +-
And the pawn is free to promote.