The encoding of the message body and the mail headers are two different kind of things. The latter is specified in RFC 2047.

Although I know next to nothing about View::Email::Template, I think you should try

my $subject = encode('MIME-Header', 'Pedido de Orçamento');
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which would create an RFC 2047 compliant subject line (provided it is fed a properly encoded (UTF-8) input string).  As this thread seems to indicate (I confess I only skimmed it, so I could be wrong), this type of header encoding is currently not being done automagically.