Does connecting a PTZ reduces the available channels on DVR?

Hi,

I am planning to buying a PTZ plus a good DVR however in my research phase i have come across a few POS which says the DVR is 8 channels, connect one PTZ and 3 cameras.

for instance see attached image where is says its a 16 channel DVR and can connect upto 4 cameras

thanks in advance

Brochure/Specs never QC properly ?