Ok, I'm in late than :) and also Voice Control misses the ability to pass variables to tasks...
I don't know how EVA works, but currently I can add such feature modifying the Tasker Action in order to accept an additional (and optional) parameter in form of a free text, that would be passed as is as a local variable called something like "%voice_control_text".
The end result would be something like:
- Activate task "My Task" with "the value to pass"
However, this way, the variable type matching and selection of Voice Control cannot be used (for example, to pass a contact name to start a call from Tasker, it would need to handle incorrectly recognized names manually in the task itself).
A better approach would be to tell, from the executed task, if Voice Control should asks for additional variable and with which expected type and name. However I don't know if it is currently possible with Tasker: as far that I can see from Tasker documentations, currently external applications can only know if a task has been successfully executed or not, but they can't receive any data back from the executed task.
A less generic solution, but a lot more powerful, could be some sort of "action builder" feature inside Voice Control, that would allows to create completely new voice actions linked to a specific tasks, where it would be possible to tell the expected local variables names among with their types, specifying for new actions a dedicated list of specific "phrase patterns" to use to activate the task (in the same way as the current action activation phrases customization works). However it would require quite some time to be added, but I could try to add it in the next major version (Voice Control 2.3.0).