There are a few Kosher gelatin products that are also vegan, including Lieber's Unflavored Jel and Carmel (brand) Unflavored Gel/Dessert. These products sub for "regular" gelatin, so you don't have to worry about tweaking the recipe. Do note that NOT all Kosher gelatins are vegetarian--some use fish bones, which aren't vegan friendly.
I'm inclined to doubt that pectin would work. It needs to be cooked with a lot of sugar and a fair amount of acid to set up, it's not simply a matter of heat like with gelatin. Agar-agar might work, but it's not a direct substitution, so maybe not something you want to risk.
Is it the pumpkin mousse parfaits from the food network? You could probably use something stiffer (and more fat, which is more stable) than cream, like mascarpone or cream cheese in the pumpkin mousse and it would hold up a little better, maybe even whisk the pumpkin mixture over a bain marie to cook the eggs and get them to set up. Or, if you'll have time to make them closer to serving, you could just leave the gelatin out and have it be soft. Or freeze it - semifreddo!