How many sensors will work in an Arduino for home automation?


As I am thinking to do a Home automation using Arduino, using Light sensor, temperature control , motion sensor , gas leakage sensor , fire detection sensor , hall effect sensor for Light on/off , fan on/off and fan speed control , motion detection , alarm for gas / fire detection , door open/close respectively. But my question is how many sensors will work at a time in at an Arduino board?
And is it possible to control Arduino by using PIC or i.MX6 Dual Lite/Solo?

If the sensors use I2C then the limit is 128 devices on the bus, but they each have to have a unique address which are sometimes "hard-coded" on the device by the manufacturer. The Arduino Wired library is used to read/write I2C and it only takes two pins. I2C is also sometimes called TWI (Two Wire Interface). The PIC can do I2C, not so sure about the i.MX6 but I've controlled an Arduino over I2C using a Raspberry Pi.