"Through" means including the mentioned date. For instance, if Susie Wiles is dismissed or resigns on March 10, 2025, then "through January 20, 2025" will resolve YES and all others will resolve NO.

After inauguration, as soon as Wiles stops serving as Donald Trump's chief of staff, all market options will resolve either YES or NO. At that point, resolutions will be final, regardless of whether she later begins serving as his chief of staff again. If Susie Wiles is not serving as Trump's chief of staff on inauguration day (January 20, 2025), for any reason, then all options will resolve NO.

I don't know if there is a technical way to determine whether someone is "officially" serving as a chief of staff for a president of the United States, so I will rely on press statements and/or announcements from the White House and/or widespread reporting to determine the time, if any, Wiles is no longer serving as Trump's chief of staff.