Can i file for taxes if i have children and are receiving cash aid?

If government assistance is your only source of income, then you have nothing to file a tax return for.  You cannot get earned income credit or Additional Child Tax Credit without income earned from working.

The money you hear about people getting for just filing a tax return claiming kids requires you to  have some earned income (wages or self employment). Without earned income, you are not eligible for the "refundable" Earned Income Credit or Additional Child Tax Credit.