In principle yes. I gave up meat three months ago (September 2011). And I replaced them with nuts, somewhere in 50-100gr. a day. I gained weight 3 kg.(6,6 pounds) – I got from 92 Kg (209 pounds) to 95 kg, and that at a height of 1.73 m .
But depends on many factors. If you do sports or exercise, peanuts will not make you gain weight, plus it’s a big difference between ripe and the roasted peanuts.