Show week numbers

Considering the fact that grouping of date is not there in pivot table, we suggest you to go with an additional column to write down the week numbers
Use the formula:
="Week "&WEEKNUM(A2)
Where A2= Date
Once the above done, use Pivot Table and drag down the week number to Row Label and amount to Values. After that Insert a Pivot Chart

Shareez idea is the best one, but if is not possible for you to add a helper column, then try some pivot grouping: https://www.contextures.com/xlPivot07.html