This cannot be emphasized enough: in the Grand Overall Design, gratitude is everything. With Consciousness being the driver of what Rupert Sheldrake calls the Morphogenic Field, the concept of gratitude is essential to the human mind being able to manifest its own reality.
So yes, quite literally the experience of gratitude or appreciation is instrumental in actually making real whatever one is being grateful for. The real effective manifestor however knows that still, manifestations will always happen in a way that all of Source wins because of it. One simply cannot manifest stuff by taking it away from someone else.