Any compressor with sidechain options can do this. I'm sure Cubase has one..
You need to put the compressor on the guitar track and take the rithmic sound as a sidechain input to the compressor.
So the compressor won't react to the guitar anymore but react to the content of the other track...
Once it's done, you need to put the treashold, ratio, attack and release to get the results you want.. it usually need a fast attack and release setting but it depends on what you are aiming for.

To have better understanding on how a compressor work, I did a video a while back :

An informative reply, thank you (and to your family of identical musicians). However, I'm not clear how to get the drum machine signal to control the sidechain. I suspect that Cubase's basic VSTDynamics processor only uses a sidechain as a filtered signal from the main input, for purposes such as de-essing. There seems no way to have a different signal into it. See here.

Perhaps there are other VST compressor/gate plug-ins that do allow a second signal input.

In the plugin I see here, it doesn,t seem to support sidechain.
Search for the Orange icon like in the image below :

Next you need to activate a send from the rithmic track to the sidechain input..
Hope it helps.. ;)

You might want to give Reaper a try. It handles sidechaining and parameter modulation in the DAW rather than in the plugins, which means that you can have any plugin parameter control any other plugin parameter.

The demo is free.