In online version 9, is there a way to see how many times users executed specific report? It is possible on-premise by querying the ReportServer database.
Microsoft came up with Activity Logging which you can enable/use/search the audit data from O365 Admin center. This covers a broader capability from O365 umbrella services including CRM user activities, but definitely we can get more useful telemetry/audit data/insights compared to previous solutions.
I see what you want as well.
Report Viewed - Logging when a report is viewed. Critical customer content information might be displayed on the report.