Let me guess:
I assume we are in the key of B♭ major, the Cm7-F7 is a ii7-V7 -> cadence in B♭ (at the end of the tune).
This means F7 and F#Maj7 are unrelated, they have nothing in common. So this is a "harmonische Rückung" (as we say in German - I'm still looking for the English term.)
Modulation B♭ -> D♭
F#Maj7-G# (probably G#7) could be (or will be?) (IV7-V) I -> C# which would be a modulation (D♭) to the mediant of Bb -> C#=Db i.e. (in this case F#Maj7-G# should be better notated by its enharmonic equivalent chords:
G♭Maj7-A♭ -> (IV7-V7) D♭
So in my analysis in the final cadence Cm-7-F7 -B♭ the tonic B♭ is skipped in purpose to modulate to D♭.
I've found this explanation for what I mean by "harmonische Rückung" :
Phrase modulation: Phrase (also called direct, static, or abrupt) modulation is a modulation in which one phrase ends with a cadence in the original key, and begins the next phrase in the destination key without any transition material linking the two keys. This type of modulation is frequently done to a closely related key—particularly the dominant or the relative major/minor key.
This describes exactly what I mean in my analysis of the progression above.
A direct modulation occurs when a chord in the previous key is followed directly by a chord in the new key. In other words, there is no smooth transition or overlap between keys, just a direct movement from one key to the next. This often happens at phrase boundaries, with the old-key tonic ending one phrase and the new-key tonic beginning the next. When a direct modulation happens across a phrase boundary, it is also called a phrase modulation.
While I have to add:
In your progression you could consider (ii7-V7) and the following (IV7-V) as a smooth transition.