The current ado in the Senate has nothing to do with witnesses or evidence at this point. It's about changing the prescribed order of the trial based upon the Clinton Impeachment as to when witnesses may be called.
Let's see what today brings.
https://www.cbsnews.com/live-updates/trump-impeachment-trial-senate-proceedings-set-to-begin-as-rules-come-into-focus-2019-01-21/
The McConnell resolution delays votes on subpoenaing witnesses and documents until both sides finish presenting their opening arguments. A simple majority of senators — 51 votes— is needed to approve the resolution, amendments and other motions. There are 53 Republicans in the Senate and 47 Democrats, including two independents.
https://www.businessinsider.com/trump-impeachment-trial-opening-arguments-live-updates-2020-1
President Donald Trump's impeachment trial is set to resume in earnest Wednesday as the two sides begin presenting their opening arguments for and against Trump's removal from office.