Final answer:
Empress Theodora played a pivotal role in convincing Emperor Justinian not to flee during the Nika riots, leading to a counter-attack that helped save his reign. The exact number of sports fans killed is not specified in the provided historical context.
Step-by-step explanation:
The question refers to a historical incident involving Empress Theodora and Emperor Justinian during the Nika riots. In a famous episode from early in Justinian's reign, as a revolt threatened his rule, Empress Theodora is noted for discouraging Justinian from fleeing. Instead, she convinced him to order a counter-attack, which proved crucial in suppressing the revolt. This event does not elaborate on the specific number of sports fans (who were part of the revolt) slaughtered after the suppression of the revolt but is noted for the significant influence Theodora had on Justinian’s decision to stay and face the revolters, which may well have saved his reign and defined the history of the Byzantine Empire.