I'd rotate the graphics before-hand and restore afterwards:
my $pdf = PDF::API2->new( -file => "$pdffile" );
my $page1 = $pdf->page;
my $photo1 = $page1->gfx;
my $photo_file1 = $pdf->image_gif($img1);
-rotate => 45,
-translate => [my $_x = 100, my $_y = 50],
There's likely to also be some translation involved depending on what corner you want to pivot from.