What do show the console-logs?
$w("#repeater1").onItemReady( ($w, itemData, index) => {
console.log(itemData.youtube)
console.log(itemData.pintrest)
console.log(itemData.instagram)
console.log(itemData.fb)
console.log(itemData.twitter)
console.log(itemData.linkedIn)
if(itemData.youtube === null) {$w("#image3").hide();}
if(itemData.pintrest === null) {$w("#image4").hide();}
if(itemData.instagram === null) {$w("#image5").hide();}
if(itemData.fb === null) {$w("#image6").hide();}
if(itemData.twitter === null) {$w("#image7").hide();}
if(itemData.linkedIn === null) {$w("#image8").hide();}
});