It looks like the pattern just uses single crochets all the way, so i think that if you wanted to just make a knit gauge swatch to get roughly the same gauge, you could probably do plain stockinette or garter stitch.
Also, you probably won't need as much yarn as the pattern calls for, as crochet takes more yarn than knitting, but you might just want to buy it all since it only takes 3 balls, and you might want to make your scarf longer or a bit wider.
Here's some more information for you:
Converting patterns
(This is for converting knit to crochet, but the priniciples are the same).