This is what I'm using to upload a csv to replace a HubDB table/db via CURL and OAUTH2

hubdb - import table

/* 
 * table_id - This is the ID of the table/database we are updating
 * $csv_file_name - This is the full path of the CSV file ($csv_file_name = __DIR__.'/import/2017-05-01-FL.csv')
 */

function upload_table($table_id, $csv_file_name) {
    $accessToken = $_SESSION['accessToken'];
    $url = "https://api.hubapi.com/hubdb/api/v1/tables/$table_id/import";
    $csv_file = new CURLFile($csv_file_name,'text/csv');
    $config_json = '{"resetTable":true,"skipRows":1,"format":"csv","columnMappings":[{"source":1,"target":1},{"source":2,"target":2},{"source":3,"target":3},{"source":4,"target":4},{"source":5,"target":5},{"source":6,"target":6},{"source":7,"target":7},{"source":8,"target":8},{"source":9,"target":9},{"source":10,"target":10},{"source":11,"target":11},{"source":12,"target":12},{"source":13,"target":13}]};type=application/json';
    $post_data = array(
      "file" => $csv_file,
      "config" => $config_json
    );
    $curl = curl_init();
    curl_setopt($curl, CURLOPT_VERBOSE, true);
    curl_setopt($curl, CURLOPT_HEADER, false);
    curl_setopt($curl, CURLOPT_POST, true);
    curl_setopt($curl, CURLOPT_URL, $url);
    curl_setopt($curl, CURLOPT_POSTFIELDS, $post_data);
    curl_setopt($curl, CURLOPT_HTTPHEADER, ["Authorization: Bearer $accessToken", "Content-type:multipart/form-data"]);
    $response = curl_exec($curl);
    $status = curl_getinfo($curl, CURLINFO_HTTP_CODE);
    curl_close($curl);
    if ( $status != 200 ) {
        $message = "Error: call to URL $url failed with status $status, curl_error " . curl_error($curl) . ", curl_errno " . curl_errno($curl);
    } else {
        $message = is_json($response) ? decode_upload_response($response) : 'There Was an Error Understanding Response: '.$response;
    }
    return $message;
}