要实现将QTableView控件的数据以及合并单元格保存为.xlsx文件，需要使用Qt的QXlsx库。以下是一个简单的示例代码：

#include <QApplication>
#include <QTableView>
#include <QStandardItemModel>
#include <QFileDialog>
#include <QAxObject>
#include "xlsxdocument.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QStandardItemModel model(4, 3);
    model.setItem(0, 0, new QStandardItem("A"));
    model.setItem(0, 1, new QStandardItem("B"));
    model.setItem(0, 2, new QStandardItem("C"));
    model.setItem(1, 0, new QStandardItem("D"));
    model.setItem(1, 1, new QStandardItem("E"));
    model.setItem(1, 2, new QStandardItem("F"));
    model.setItem(2, 0, new QStandardItem(""));
    model.setItem(2, 1, new QStandardItem(""));
    model.setItem(2, 2, new QStandardItem("G"));
    model.setItem(3, 0, new QStandardItem(""));
    model.setItem(3, 1, new QStandardItem(""));
    model.setItem(3, 2, new QStandardItem("H"));
    QModelIndex topLeft = model.index(0, 0);
    QModelIndex bottomRight = model.index(1, 1);
    model.setData(model.index(2, 0), QVariant(topLeft), Qt::UserRole);
    model.setData(model.index(2, 1), QVariant(bottomRight), Qt::UserRole);
    model.setData(model.index(2, 2), QVariant(true), Qt::UserRole);
    model.setData(model.index(3, 0), QVariant(bottomRight), Qt::UserRole);
    model.setData(model.index(3, 1), QVariant(true), Qt::UserRole);
    model.setData(model.index(3, 2), QVariant(bottomRight), Qt::UserRole);

    QTableView tableView;
    tableView.setModel(&model);
    tableView.show();

    QString filePath = QFileDialog::getSaveFileName(nullptr, "Export to Excel", "", "Excel Files (*.xlsx)");
    if (!filePath.isNull())
    {
        QXlsx::Document xlsx(filePath);
        QStandardItemModel *tableModel = qobject_cast<QStandardItemModel *>(tableView.model());
        for (int row = 0; row < tableModel->rowCount(); ++row)
        {
            for (int column = 0; column < tableModel->columnCount(); ++column)
            {
                QModelIndex index = tableModel->index(row, column);
                QVariant data = tableModel->data(index, Qt::DisplayRole);
                xlsx.write(row + 1, column + 1, data.toString());
                QVariant mergedData = tableModel->data(index, Qt::UserRole);
                if (mergedData.isValid())
                {
                    QModelIndex topLeft = mergedData.toRect().topLeft();
                    QModelIndex bottomRight = mergedData.toRect().bottomRight();
                    bool isMerged = tableModel->data(index, Qt::UserRole + 1).toBool();
                    if (isMerged)
                    {
                        xlsx.mergeCells(QXlsx::CellRange(topLeft.row() + 1, topLeft.column() + 1, bottomRight.row() + 1, bottomRight.column() + 1));
                    }
                    else
                    {
                        for (int r = topLeft.row(); r <= bottomRight.row(); ++r)
                        {
                            for (int c = topLeft.column(); c <= bottomRight.column(); ++c)
                            {
                                if (r == row && c == column) continue;
                                xlsx.writeBlank(r + 1, c + 1);
                            }
                        }
                    }
                }
            }
        }
        xlsx.save();
    }

    return a.exec();
}

在此示例代码中，首先创建了一个QStandardItemModel模型，并在其中添加了一些数据和合并单元格信息。然后创建了一个QTableView控件，将该模型作为其数据源，并显示出来。接着调用QFileDialog对话框让用户选择保存的.xlsx文件路径，如果用户选择了文件路径，则使用QXlsx库在该路径下创建一个.xlsx文件，并将QTableView控件中的数据和合并单元格信息写入到该文件中。