"As Jonah entered the city, he began at once to “cry against” it the message, “Yet forty days, and Nineveh shall be overthrown.” Verse 4 . From street to street he went, sounding the note of warning. PK 270.1"
"Arise, go to Nineveh, that great city, and cry against it; for their wickedness is come up before me."
EGW directly quotes and references Jonah 1:2, making it an explicit allusion rather than a thematic parallel.
"As king and nobles, with the common people, the high and the low, “repented at the preaching of Jonas” ( Matthew 12:41 ) and united in crying to the God of heaven, His mercy was granted them. He “saw their works, that they turned from their evil way; and God repented of the evil, that He had said that He would do unto them; and He did it not.” Jonah 3:10 . Their doom was averted, the God of Israel was exalted and honored throughout the heathen world, and His law was revered. Not until many years later was Nineveh to fall a prey to the surrounding nations through forgetfulness of God and through boastful pride. [For an account of the downfall of Assyria, see chapter 30.] PK 270.4"
"The men of Nineveh shall rise in judgment with this generation, and shall condemn it: because they repented at the preaching of Jonas; and, behold, a greater than Jonas is here."
Ellen White directly references Matthew 12:41 in this passage.
"And God saw their works, that they turned from their evil way; and God repented of the evil, that he had said that he would do unto them; and he did it not."
Ellen White directly references Jonah 3:10 in this passage.
"So the people of Nineveh believed God, and proclaimed a fast, and put on sackcloth, from the greatest of them even to the least of them."
The EGW passage describes the repentance of the people of Nineveh and God's subsequent mercy. This directly relates to the description of their repentance in Jonah 3:5. The connection is a clear thematic parallel.