connection question

I currently have xfinity internet with a xfi gateway. There are two coax cables from the street coming in, one goes to an 8 way splitter and one goes to a power supply. There is a coax going from the 8 way splitter to the gateway.  I am going to be adding tv to my service. my question is this, do i connect the tv box to the current 8 way splitter, or do i need to split the signal before it goes to the current splitter.