<?php
$responses = array('A=1', 'B=2', 'C=3');
foreach ($responses as $value) {
    $split = explode('=', $value);
    $array1[$split[0]] = $split[1];
}
print_r($array1);
?>

Array
(
    [A] => 1
    [B] => 2
    [C] => 3
)