You can change the orientation in the xlsxtemp object:
xlsxtemp.Open(...);
xlsxtemp.PrintLandscape := false;
pdf := ...
Or you can change the orientation directly in Excel in templatecheda.xlsx file.
PdfExport will always use the orientation that is saved in the file. Note that there might be the case that the xlsx file doesn't have any orientation saved, in this case the orientation is undefined, and you should use xlsxtemp.PrintLandscape := true always.