I have a iwatch 2, will the new X work with the magnet charger i already have?

Hi

No - the Apple Watch Magnetic Charging Cable is not compatible with iPhone X:

Apple Watch Magnetic Charging Cable (2 m) - Apple

Compatible wireless chargers for iPhone X are available via the Apple Online Store. For example:

Belkin Boost Up Wireless Charging Pad - Apple

Does that mean you can’t charge an Apple Watch with the Belkin qi boost up charger?

Yes - that product is not compatible with Apple Watch.