The ornamental design for a fruitcupinfuser, as shown and described.
FIG. 1 is an upper front perspective view of a fruit cup infuser showing a cross section of the fruit cup infuser taken in the direction of line I-I in FIG. 4;
FIG. 2 is a lower front perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a top view thereof; and,
FIG. 5 is a bottom view thereof.
The broken lines shown in the drawings represent environmental structure in FIGS. 1-5 that form no part of the claimed design.