Someone told me that I should empty my gas tank, put new gas and some chemical over the winter. Can someone please shed some light on this topic. Thanks

 

You don't need to drain the gas, on a yearly basis.
It's not a bad idea every 2-3 years to drain, but mostly for the chance to
pull the petcock and clean the debris form the screens and bottom of the tank.

You DO want to add a fuel stabilizer (Stabil, is a common brand)
and top off the tank. The reason is to prevent condensation from forming
on the inside of the tank walls, (from temp changes in a typical garage/carport).
The tank has to be vented, so there is no way to prevent humidity to be in the tank.

a. it rusts the tank walls
b. it compromises the fuel left in the tank, as it runs down the sides and into the gas.

It also helps to either, remove the battery to a warm location
and/or put a "smart" trickle charger/maintenance-monitor on it.
They're a little 2amp brick that monitors the battery,
so it doesn't over-charge/damage it.
Usually about $40, or cheaper, if you hunt around.

Do a couple of searches on 'winter storage tips motorcycle',
for more in-depth suggestions.

Hope this helps, Ern