This is a very dangerous comparison and shows a fundamental misunderstanding of what Trump is doing.
Nixon's approval rating dropped like a rock when what Nixon had done made it into the public eye. Over a (relatively) short period of time Nixon, who history often forgets was massively popular (we will never see an EC spread like 1972 again), lost popularity because of a rapid fire sequences of events (The Saturday Night Massacre, the release of the tapes, the smoking gun tape, etc) that brought information about what Nixon was doing into the public eye. There never was any big social discussion about what whether or not what Nixon was doing was wrong.
Trump could not be further from this. What he's doing isn't being hidden, indeed he's publicly bragging about it. Trump has fifty "Nixon Moments" before breakfast on an average day.
Trump openly admitted to doing what he was impeached for doing what about 4, 5 days was it into this impeachment proceedings and he's still in office.
There's no smoking gun with Trump because he's holding the gun in his hand and firing it all the time while screaming "LOOKIT ME I'M SHOOTING THE GUN RIGHT NOW! EVERYBODY SEE ME SHOOTING THE GUN! WATCH ME SHOOT THE GUN!"
Nixon didn't "LOL lookit the triggered libs" for a bunch of reality denying cultists.