For a similar question above, it was assumed that, the gematria of yud being ten, the additional yud may represents the Ten Commandments, and that perhaps the spelling implied that the Jews were rescued from the decree in the merit of their teshuva (“repentance”) (see Esther 9:27).
The total gematria of Yehudim with the extra yud (10+5+6+4+10+10+40=85) is 85, the same gematria as peh (“mouth”) (80+5=85). This represents prayer, which is what rescued the Jews from the decree.
Interestingly, with the above verse (Esther 8:1), there seems to be a reference to two mouths, perhaps implying a parallel with the verse (Shemos 33:11) in which H-Shem praises Moshe as one with whom He communicates “peh el peh” (“mouth to mouth”). Part of the reason the Jews were saved was in the merit of Moshe, as the Midrash (Esther Rabba 7:14) says explicitly. Throughout Jewish philosophy, Moshe represents the Torah that he received and taught. Taken all together, the Jews’ repentance, prayer, and acceptance of Torah rescued them from this terrible fate.