Works fine for me:

use CGI;
my $q = CGI->new();

print $q->textfield( -name=>'OutputLog',-override => true, -value => '
+test' );
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Output:

$ ./882118.pl
<input type="text" name="OutputLog" value="test" />
                                           ^^^^
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As you can see, the generated HTML text field has the value "test".

Maybe your problem is somehow in the wider context you're using this snippet in...?  Could you provide a stripped down, but self-contained CGI script that demonstrates the issue you're having? (within <c>...</c> tags please)