I'm using soundforge to record into. The problem is that I'm not getting anything out of my dat (signal wise).
I don't think it's reasonable, given the information available so far, to conclude you're not getting signal out of your DAT. Before we make that conclusion, we need to verify at a minimum:
[1] all physical connections and cables are connected and functioning properly
[2] proper soundcard drivers are installed and working
[3] soundcard is configured correctly for digital input
[4] proper Soundforge configuration for recording a digital signal
As I look more closely at your post, looks like you're using the Pro Digital 7-in cable which transmits a S/PDIF signal over coax wire with RCA connectors. The specs on your M-Audio sound capture device indicate it may receive a S/PDIF
optical signal with 1/8" connector. Based on this, it appears you need:
[a] a sound capture device that accepts S/PDIF coax, or
a 7-pin > optical cable, or
[c] a coax > optical digital format converter