In his story, "The Interlopers," Saki seems to feel that life contains a select number of opportune moments, and if these moments are not utilized, fate will predominate.

For years Ulrich von Gradwitz and Georg Znaeym have harbored great enmity for each other, and if it were not for this terrible animosity between the two men, the feud over forest land may have died out. So, von Gradwitz pursues his enemy one night, heedless of an approaching storm. Then, when the two men come vis-à-vis, there is the slight hesitation of civilized men and they do not shoot. As fate would have it, lightning strikes a huge beech tree just as each man is ready to shoot the other, and they are trapped.

Pinioned in such positions that they can speak, but not touch, von Gradwitz offers his old enemy his flask; further, he proposes that they terminate their feud. Znaeym accepts and jokes at how the others will be surprised that such enemies have made peace. They promise each other that no matter which of their parties arrive to help them, they will provide the other with food and good care. Unfortunately, however, it is too late because Nature intercepts their attempts with the fateful approach of the greatest of enemies:

“Are they your men?” asked Georg....“No,” said Ulrich with a laugh, the idiotic chattering laugh of a man unstrung with hideous fear. “Who are they?” asked Georg quickly, straining his eyes to see what the other would gladly not have seen. 

Fate ends the new friendship and the old animosity with the approach of the Russian man's greatest fear in the woods: wolves.   

This is a great question.  First, we should say that the word "fate" is not used in the short story. Therefore, if Saki has an understanding of fate, then it must be deduced from his story. 

In my opinion, there is an understanding of fate because both Gerog and Ulrich believe that the other is the interloper. They believe that they could own the stretch of land. They do no consider that their false understanding would be corrected by nature itself. So, when there is a storm, a tree is felled and the men are pinned underneath. In time, they reconcile, but this means nothing, because they are the true interlopers. 

At the end of the story, wolves come, and the implication is that the men die. How fitting for men who trespass with no understanding of their hubris. 

The point behind this is that fate led them to this place to realize this point. The theme of fate is understated but present.