Is it possible to generate separate 8 different duty cycles pwm on 8 pins of pic16f877a? If yes then how?

 

Not using the hardware, you would need to write a complicated software PWM routine, maybe not that complicated, ive never done it, but thats the way it would be done.

 

BTW by duty cycle did you mean frequency? If you just meant duty cycle with 1 frequency that wouldn't be too bad

 

Is it possible to generate separate 8 different duty cycles pwm on 8 pins of pic16f877a? If yes then how?

You can not do it on hardware with this PIC but you can do it with a dsPIC which has up to 8 different PWM channels.