So I had a buddy ask me if he can pulse wave winter soldier while he is in the nest. I was previpreviously told no by someone I played against a few months ago. The reason he gave me is cause you can't draw line of fire to him to pulse wave him. Is this correct? Just asking so I can let my buddy know.

yes. Lines of fire can't ignore anything if they can't be drawn.... as far as I know, but I'm no expert.

Please quote the effects in question. Not only does it help eliminate confusion (not everyone necessarily know who Winter Soldier is or what he's doing in a Sniper's Nest), but a second reading can often reveal the answer. For reference:

SNIPER'S NEST: Once per game, give Winter Soldier a power action, place three Sniper's Nest terrain markers on the map, and place Winter Soldier in one of these squares. When he occupies one of these markers, he can use Ranged Combat Expert, lines of fire can't be drawn to him, and he may not be given actions except power actions to use Ranged Combat Expert. Once per turn, you may place Winter Soldier in the square of a different one of his Sniper's Nest markers. When an opposing character becomes adjacent to one of these markers, roll a d6 that can't be rerolled. On a result of 1 or 2, place Winter Soldier in the square of a different one of his Sniper's Nest markers. On a 3-6, remove the marker and, if Winter Soldier occupies that square, place him in another of his Sniper's Nest markers if there is one on the map.

He doesn't block LOF with the Nest. Instead, LOF can't be drawn to him at all. That's an important distinction because:

PULSE WAVE Give this character a ranged combat action even if it is adjacent to an opposing character; the area of effect for this attack is half the character’s range value. Draw lines of fire to all other characters within the area of effect, including at least one opposing character; these lines of fire ignore all game effects except for walls, blocking and elevated terrain. Game effects possessed or used by characters with a line of fire drawn to them are ignored until the action has been resolved. If a line of fire is drawn to more than 1 character, this character’s damage value becomes 1 and is locked. Each character hit is dealt damage.

PW requires that LOF be drawn to ignore anything. Sniper's Nest says that can't happen.

Your buddy was correct.

Pulse Wave ignore most things. However it doesn't ignore anything until it draws it's Lines of Fire. So if a game effect on a character prevents a Line of Fire from being drawn it then Pulse Wave cannot ignore that game effect as it preceeds PW's ignore.

However note that if the game effect states that a Lines of Fire drawn to the character is blocked then Pulse Wave will ignore that game effect as it allows you to actually draw the Line of Fire and PW ignore comes into effect.