On the stack

[Deathseide]

Can the mill triggered effect of a  {Gaea's Blessing} be stopped by playing a  {Suffer the Past}?

[scarsabrex]

Can the mill triggered effect of a  {Gaea's Blessing} be stopped by playing a  {Suffer the Past}?

Sorta. You can prevent x cards from being returned to the deck.

[Millionlittlee]

Can the mill triggered effect of a  {Gaea's Blessing} be stopped by playing a  {Suffer the Past}?

depends on what you want to do
if you want to stop the cards from going back into the library then you cast it on the stack, but if you want to get rid of gaea's blessing then you wait till after it resolves, its effect goes on the stack and that is the point to exile it