I've reworked your code somewhat. The most important change is to add strictures (use strict; use warnings; - see The strictures, according to Seuss), but I've also added the start of collision detection (which may have an off by 1 bug in it), allowed the number of display rows to be set and refactored the code somewhat (in part to show off some Perl stuff like join and arrays).

This code is not tested because I can't quickly find a working ANSI Terminal emulation for Windows 8.

#!/usr/bin/perl
use strict;
use warnings;
use Term::ANSIScreen qw/:color :cursor :screen/;
use Term::ReadKey;

my $rows = 50;

ReadMode('noecho');
cls;
setscroll (1, $rows);
locate 1, 1;

my @screenRows;

# Create the initial screen
push @screenRows, newRow() for 1 .. $rows;
print join "\n", @screenRows, '';

my $wait   = 1;
my $skierx = 40;

while (1) {
    if (defined(my $key = ReadKey(-1))) {
        if ($key eq "j") {
            --$skierx;
        } elsif ($key eq "k") {
            ++$skierx;
        } elsif ($key eq "x") {
            exit;
        }
    }

    # Generate and show a new line    
    shift @screenRows;
    push @screenRows, newRow();
    print $screenRows[-1];
    
    # Collision detection
    if (' ' ne substr $screenRows[$rows / 2], $skierx - 1, 1) {
        locate $rows, 1;
        print "Crash!\n";
        exit;
    }
    
    # Show skier's updated position
    locate $rows / 2, $skierx;
    print "V";

    # wait
    select(undef, undef, undef, $wait);    #pauses here
    $wait -= 0.003;
}


sub newRow {
    my $col = int(rand(80));
    return ' ' x $col . 'T' . (' ' x (78 - $col));
}
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