I went and looked at the pattern. Since the repeat of the lace pattern is over 14 rows you have 14X8 or 112 stitches plus the extra first and last row that will be used for seaming(don't mess with those 2 rows), so you have plenty to pick up from. I don't know what you are doing, but to get 80 stitches you will need to pick up 10 along the side of each of the lace repeats of 14 stitches 8X10=80. This will work out perfectly all the way around if over the 14 side stitches you pick up 2, then skip one, pick up 3, skip 1, pick up 2, skip 1, pick up 3, skip 1. That covers the 14 lace stitches and brings you right around to begin the next lace pattern in the same place, and you have picked up 10 along the 14. Repeat the sequence between the * *s 8 times and you will have picked up 80 around.
Where you may be having problems is seeing where each of the stitches along the sides are that are candidates for being picked up. If you can't see them well enough to pick them up in such a systematic way just try to space 10 picked up stitches as evenly as you can (no biggie if not perfect) over each of the 8 lace repeats. 8X10 will give you your 80. Good luck picking up.