What does the Prologue say about fate and what does Romeo say about fate in Act 1, Scene 4 of Romeo and Juliet?
The prologue famously describes the lovers as "death-mark'd", that the two lovers, before they have even met, and before the play has even begun, are picked out in the stars to end up dead. Of course, that doesn't mean, necessarily that their deaths will be early ones, as many critics sometimes assume. And "death", to the Elizabethans, also meant "orgasm", so death-marked might have had a totally different connotation.
But many critics read that line of the prologue as referring to the fact that Romeo and Juliet will end up dead early, that their love is somehow picked out to end badly before it has begun.
Romeo says something similar in Act 1, Scene 4, as you suggest:
... my mind misgives
Some consequence, yet hanging in the stars,
Shall bitterly begin his fearful date
With this night's revels and expire the term
Of a despised life, clos'd in my breast,
By some vile forfeit of untimely death.
Something hangs in the stars, Romeo thinks, waiting to go wrong, waiting to begin his downward course of action with that same night's party. It will end in the expiration of the life shut up in his breast: with his death.