$ cat t.pl
#!/usr/bin/perl
use strict;
use warnings;
use feature ':5.10';

my %Variables = ( NAME=>'Roboticus', STATE=>'KY', BIRD=>'Cardinal' );

my $Template = '{NAME} lives in {STATE}.  {FOO}.';

for my $t ($Template=~m/{([A-Z]+)}/g) {
    $Template =~ s/{$t}/$Variables{$t}/g if exists $Variables{$t};
}

say $Template;

$ perl t.pl
Roboticus lives in KY.  {FOO}.