Ok. So the US says so, a number of states aligned with the US, and the Venezuelan opposition. Still no evidence.
None of it is proof, but all of it is evidence. Given that you have provided zero evidence to the contrary, the balance of evidence seems clear.
I gather that the Nobel Prize does not convey a tendency for honesty.
"[Machado] claimed her party's candidate, Mr Gonzalez, won by a landslide and Ms Machado said she could prove this because she had receipts from more than 80% of polling stations."