Ok so I placed a gallery in a test app just to show you how it works in a gallery, may need to edit slightly to match your needs but here goes.
My gallery has a items value of
CoachingDatabase
which is just a random splist i have with dates in it so chose that
Title box in that gallery has text value of
Text(DateValue(ThisItem.DATE),"dd/mm")
and a color value of
If(
And(Day(ThisItem.DATE)=Day(Today()), Month(ThisItem.DATE)=Month(Today())), Red, Green)
which results in the following, where every date that matches today shows in red, and otherwise date is green
