Instead of {authors}, you can use
Code:
{authors:sublist(0,2, & )}
Change the 2 to the number of authors you want to see.
FWIW: I prefer using template program mode to make the parameters clearer, so I would use
Code:
{authors:'sublist($, 0, 2, " & ")'}
or even
Code:
{:'sublist(field('authors'), 0, 2, " & ")'}