All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Imams Al Bukhari and Muslim reported in a sound Hadeeth that the Prophet said: “Evil eye is indeed true.”
Imam Muslim also reported that the Prophet said: "Evil eye is the truth and if anything could precede (have effect on) the predestination it would be evil eye, and if anybody asks you to perform Ghusl (or ablution) [to give him the water so that he may perform ablution to be cured from evil eye] then do so.”
The Prophet also said: “Evil eye is the truth, it could cause a mountain to be leveled to the earth.” [Ahmad]
So, these Ahadeeth and others are enough evidence that evil eye is true.
Allah knows best.