Can you find an authoritative source that either confirms or denies the statistic in this tweet:
This activity will take some time, as to pull the right statistic you are going to need some of the background of the conflict.
When you have finished researching the conflict and various estimates of the number of Filipinos killed develop your own opinion as to the death toll.
As always, keep in mind that looking for the precise statistic is not meant to minimize events like these. In fact, if you want to contest this number think of how you might reply in a way that does not diminish the writer’s overall point about the cruelty of the event.