>>798　CellsにもSheetを指定しなきゃダメ

Worksheets("Page1").Range(Worksheets("Page1").Cells(cnt, 1), Worksheets("Page1").Cells(cnt, 8)).Copy _
Destination:=Worksheets("data").Range(Worksheets("data").Cells(k, 1), Worksheets("data").Cells(k, 8))

With Worksheets("Page1")
.Range(.Cells(cnt, 1), .Cells(cnt, 8)).Copy _
Destination:=Worksheets("data").Range(Worksheets("data").Cells(k, 1), Worksheets("data").Cells(k, 8))
End With

Dim Ws1 As Worksheet, Ws2 As Worksheet
Set Ws1 = Worksheets("Page1")
Set Ws2 = Worksheets("date")
Ws1.Range(Ws1.Cells(cnt, 1), Ws1.Cells(cnt, 8)).Copy _
Destination:=Ws2.Range(Ws2.Cells(k, 1), Ws2.Cells(k, 8))

好きな書き方でどうぞ