Will the improvement of power factor will increase the efficiency?

Efficiency is defined as the ratio between the output power and the input power of a machine, expressed as a per unit or percentage.

Power factor improvement has absolutely no effect on the behaviour of a load. All it does is to reduce the magnitude of the load current. A reduction in load current means that less copper can be used in the supply of energy to the load. However, it doesn't effect either the output or input power of the load. So the answer is no, power factor has no effect on the efficiency of a load.

You could argue, however, that if improving the power factor of a load reduces the supply current, leading to lower line losses, then there is an improvement in the efficiency of the supply system.