Having a child in Canada (either as PR or Citizen) will give you 5 points under the FSW eligibiility scale (67/100 minimum), but nothing under the Comprehensive Ranking Score (CRS). It has to be a brother or sister in this last case to get 15 points.
So yes it does increase your chances of becoming eligible for the FSW program itself. But once you are found eligible, it won't help you in receiving an Invitation to Apply (ITA).