Basically each timer object can run 16 timers.
Example:
BlynkTimer timer1 16 instances BlynkTimer timer2 16 instances BlynkTimer timer3 16 instances BlynkTimer timer4 16 instances
BlynkTimer timer1
BlynkTimer timer2
BlynkTimer timer3
BlynkTimer timer4
As far as i have understood there is no limitation. But you will have to stagger the timers. There should be no delays inside the functions called by the timers.
Go through this topic. It just has all the important stuff.