BangP is right, but didn't answer all your question.
A "DVD player" is a "source device" intended to extract audio and video information from a DVD and send them in a suitable form for processing to an external device(s). It can't serve as a "receiver" (which is a combination of a radio tuner and an amplifier) since it doesn't have the capability to amplify the audio signal nor to connect speakers. To get surround sound from a DVD you MUST have some form of multi-channel amplifier (usually an A/V receiver) to process and amplify the low level signal from the DVD player.
The best way to tell if you can get surround sound from your equipment is to see if it has 5 or more pairs of external terminals to which speakers can be attached (See image at Link 1 for a typical back panel of a budget A/V receiver. Speaker connect to the gang of 4 spring terminals marked "front speakers" at top center and the 12 round colored terminals at the upper right). DVD players on the other hand only have RCA jacks, and maybe an optical and HDMI jack (Link 2).
You are confusing your DVD player with built in DVD players in an all-in-one home theater unit (usually called an HTIB or "Home Theater in a Box"). The difference is that you have, as mentioned, a stand alone DVD player, while an HTIB is a combination of DVD player and A/V receiver.
As to your question re. cable TV, if you have a cablebox the audio output can be connected to an A/V receiver or HTIB (but not your DVD player) to get surround sound (assuming surround sound speakers are attached to the amplifier!). If it is simple cable, you can take audio from the HDTV's audio output and feed it to an A/V receiver or HTIB and may stereo sound (but probably not surround).
I understand this may appear complex, but I hope this helps explain things a bit. For more information see the last link.