How to Count Slicer Items

There is a simple solution.  You are not wanting your measure to be sliced by the dates in the visual. Therefore, just create a new calendar that is disassociated from everything and use its dates in the visual.

1. Modeling > New table

Calendar = CALENDAR(DATE(2019,1,1), DATE(2025,12,31))

2. Replace the date in the x-axis of your visual with this one.

3. You can limit the range of the x-axis to your slicer's range using visualizations > format visual > range > minimum/maximum

Now you have a chart with two straight lines (6 for total and 5 for emp_Count).

I assume you want some other data in the chart. You can make measures to refer to your new calendar. For example:

Emp_Count for date = 
VAR the_date = SELECTEDVALUE('Calendar'[Date])
RETURN
CALCULATE(DISTINCTCOUNT(EmployCount[Employ]),
          EmployCount[Date_Range] = the_date)

Or equivalently:

Emp_Count for date = 
CALCULATE(DISTINCTCOUNT(EmployCount[Employ]),
          TREATAS(VALUES('Calendar'[Date]), EmployCount[Date_Range]))

Result: