#!C:\perl\bin\perl

use strict;
use diagnostics;
use Data::Dumper;        

use CGI qw/:standard :html3/; 
use CGI::Carp qw( fatalsToBrowser );

my $nbr_of_fields = 15; # This is taken as user input

print header("text/html");
print start_html();
print start_form({-method=>"post", -action=>"test.cgi"}),br;


for (0..$nbr_of_fields - 1) {

  print textfield(-name=>"field_name$_",
                    -value=>5,
                    -size=>50,
                    -maxlength=>80);

}
 
 print hidden({-name=>"User_Input", -value=>"$nbr_of_fields"});
 print submit({-name=>'action', -value => 'Submit' }),
        end_form, end_html;

##</code><code>##

Test.cgi
--------
#!C:\perl\bin\perl

use strict;
use diagnostics;
use Data::Dumper;        

use CGI qw/:standard :html3/; 
use CGI::Carp qw( fatalsToBrowser );

my $user_input = param('User_Input');

print header("text/html");
print start_html();
 
for (0..$user_input - 1) {

  print "Filed_name$_&nbsp;:&nbsp;&nbsp;&nbsp;", param("field_name$_"),br;
}

print end_html;