It seems Nintendo Switch users will most-likely never see the day of smooth 60FPS in Fortnite.
The Nintendo Switch version of Epic Games' immensely popular battle royal experience 'Fortnite' takes some considerable losses in the performance department compared to the other platforms its available on. Unfortunately, don't expect this is going to get better with time. In a recent Reddit AMA with Fortnite's developer Epic Games, a fan asked the company if the Nintendo Switch version of the game would see an update that would increase the FPS to 60FPS, the response wasn't promising.
According to the developer, increasing the FPS cap in Fortnite for the Nintendo Switch is just "not in the cards". In fact the developer chose to remove the video game capture last year to help increase performance for the struggling Switch. This has also led to reasoning for Epic choosing not to add that feature back either. The leap from the current 30FPS on the Switch to the expected 60FPS is not a small feet, and would require large levels of optimization.
It should be noted that not many games run at 60FPS on the Nintendo Switch, and the select few that do are either Nintendo's first-party titles or low-resolution games that the developers can choose performance over graphics. The Nintendo Switch has quite some trouble running games at 60FPS at 720p, and unfortunately Fortnite will not be one of them.