Darius the Great's father was named Hystaspes, which is the Greek form of the same Iranian name, Vishtaspa. He was a satrap under Cyrus and Cambyses and is a documented Achaemenid figure. He is not the patron of Zarathustra, and the two have been run together repeatedly for well over two thousand years.
The confusion produced consequences of its own. A body of Greek apocalyptic literature circulated under the name of Hystaspes as an ancient Persian sage, and Christian writers cited it. Later Zoroastrian and Islamic-era Persian sources also place Zarathustra in the Achaemenid period, and the traditional dating that puts him two hundred and fifty eight years before Alexander appears to be built from that identification working backwards.
Modern scholarship generally rejects it. The Gathic language is archaic, close enough to the Sanskrit of the Rigveda that most specialists place the hymns somewhere in the second millennium BCE or the very early first, which is many centuries before any Achaemenid. On that dating Vishtaspa was a ruler somewhere in eastern Iran or Central Asia, in a society of cattle, chariots and small kingdoms, and there is no external record of him at all.
The atlas holds his period as unknown rather than as debated. There is no contest between reconstructions here, because there is nothing outside the tradition to argue from: no inscription, no archive, no fixed place. What would change that is an epigraphic or archival find naming him in a datable context, and until one appears the tradition's own testimony is the entire file.