my $customer  =  q(Karl Dämlich);

$customer = encode_utf8($customer);

say $customer;

my $data = {
    customer_name   => $customer,
    factoring_nr    => '123456',
    user            => 'karl',
    invoice_amount  => '50.403,50',
    number_invoices => '5',
    dispatched      => $date,
    approved        => $date_time,
    invoices        => \@invoices,
};

dd $data;

__END__

karl@host:~/mk_pdf # ./template.pl
Karl Dämlich
{
  approved        => "04.12.2015 15:24:42",
  customer_name   => "Karl D\xC3\xA4mlich",
  dispatched      => "04.12.2015",
  factoring_nr    => 123456,
  invoice_amount  => "50.403,50",
  invoices        => [],
  number_invoices => 5,
  user            => "karl",
}