The answer is "it depends"; it depends on how you import the CDs and what else you might put on the iPod. A song imported at 256 kbps AAC, which is the format used in the iTunes Store, takes up about 8.2 megabytes for a four minute song. The 64GB iPod touch has an actual usable capacity of about 59.4 gigabytes, so you can do the math from there.
Importing the CDs at a higher or lower bit rate (bit rate directly relates to quality; the higher the bit rate, all other things being equal, the higher the quality of the track) will reduce or increase the number of tracks you could put in your iPod. And of course the more apps, movies, videos, photos etc. you put in your iPod, the fewer songs you can put on it.
Regards.