To be dramatic: Will a 4.8:1 cast farther than an 8.1:1?

No.  The same reel in different gear ratios with the same brake settings should cast almost identically.  

Gear ratio has nothing to do casting distance only retreive speed.

Tom

Thanks guys - I only ask because I was watching the most recent BigBassDreams vid on YT and they were saying something about wanting a faster gear ratio reel "because I'm only casting to that one tule right there" and I wondered if that implied a reduced casting distance for higher gear reels.  

No.

29 minutes ago, Gilgamesh said:

Thanks guys - I only ask because I was watching the most recent BigBassDreams vid on YT and they were saying something about wanting a faster gear ratio reel "because I'm only casting to that one tule right there" and I wondered if that implied a reduced casting distance for higher gear reels.  

Probably because they want to get the bait back and cast again.  The gears are not engaged when the thumb bar is pressed, so retrieve speed has no influence on casting.

Only thing gear ratio would affect in the ‘cast’ would be the retrieve back. A lower gear ratio doesn’t take up as much line per 1 turn of the reel handle.