The day of their wrath refers to the time when they would punish wicked people. AT: "this is the terrible time when they will punish people" (See: [[rc://en/ta/man/translate/figs-metonymy]])
# has come
Existing now is spoken of as having come. (See: [[rc://en/ta/man/translate/figs-metaphor]])
# their wrath
"Their" refers to the one on the throne and the Lamb.
Surviving, or staying alive, is spoken of as standing. This question is used to express their great sadness and fear that no one will be able to survive when God punishes them. AT: "No one can survive" (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-rquestion]])