No, lifting weights does not cause capsule formation. There are some unproven theories that a submuscular implant pocket actually protects against capsular contracture formation. This is thought to be as a result the internal massage effect of the pec muscle on the implant and pocket. This breaks up the scar formation and softens the capsule.
Of course heavy weight lifting too early after augmentation can lead to implant rotation and seroma formation, especially is the implant is in a dual plane or submuscular pocket.